essay on life on earth

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Heritability

Convergence, spontaneous generation, geologic record.

• Hypotheses of origins
• Production of polymers
• The earliest living systems

• What is a cell?
• What is cell theory?
• What do cell membranes do?

Evolution and the history of life on Earth

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• Frontiers - What is Life?
• National Center for Biotechnology Information - PubMed Central - What is life?
• University of Minnesota Pressbooks - Introductory Biology: Evolutionary and Ecological Perspectives - Definition of Life
• University of Hawaii - Exploring Our Fluid Earth - Properties of Life
• Biology LibreTexts - The origin of life
• Khan Academy - What is life?
• Stanford Encyclopedia of Philosophy - Life
• Table Of Contents

The evidence is overwhelming that all life on Earth has evolved from common ancestors in an unbroken chain since its origin. Darwin’s principle of evolution is summarized by the following facts. All life tends to increase: more organisms are conceived, born, hatched, germinated from seed , sprouted from spores, or produced by cell division (or other means) than can possibly survive. Each organism so produced varies, however little, in some measurable way from its relatives. In any given environment at any given time, those variants best suited to that environment will tend to leave more offspring than the others. Offspring resemble their ancestors. Variant organisms will leave offspring like themselves. Therefore, organisms will diverge from their ancestors with time. The term natural selection is shorthand for saying that all organisms do not survive to leave offspring with the same probability. Those alive today have been selected relative to similar ones that never survived or procreated. All organisms on Earth today are equally evolved since all share the same ancient original ancestors who faced myriad threats to their survival. All have persisted since roughly 3.7 billion to 3.5 billion years ago during the Archean Eon (4 billion to 2.5 billion years ago), products of the great evolutionary process with its identical molecular biological bases. Because the environment of Earth is so varied, the particular details of any organism’s evolutionary history differ from those of another species in spite of chemical similarities.

Everywhere the environment of Earth is heterogeneous . Mountains, oceans, and deserts suffer extremes of temperature, humidity, and water availability. All ecosystems contain diverse microenvironments: oxygen-depleted oceanic oozes, sulfide- or ammonia-rich soils, mineral outcrops with a high radioactivity content, or boiling organic-rich springs, for example. Besides these physical factors, the environment of any organism involves the other organisms in its surroundings. For each environmental condition, there is a corresponding ecological niche . The variety of ecological niches populated on Earth is quite remarkable. Even wet cracks in granite are replete with “rock eating” bacteria . Ecological niches in the history of life have been filled independently several times. For example, quite analogous to the ordinary placental mammalian wolf was the marsupial wolf, the thylacine (extinct since 1936) that lived in Australia; the two predatory mammals have striking similarities in physical appearance and behaviour. The same streamlined shape for high-speed marine motion evolved independently at least four times: in Stenopterygius and other Mesozoic reptiles; in tuna , which are fish; and in dolphins and seals , which are mammals. Convergent evolution in hydrodynamic form arises from the fact that only a narrow range of solutions to the problem of high-speed marine motion by large animals exists. The eye , a light receptor that makes an image, has evolved independently more than two dozen times not only in animals on Earth but in protists such as the dinomastigote Erythropsodinium . Apparently eyelike structures best solve the problem of visual recording. Where physics or chemistry establishes one most efficient solution to a given ecological problem, evolution in distinct lineages will often tend toward similar, nearly identical solutions. This phenomenon is known as convergent evolution .

Life ultimately is a material process that arose from a nonliving material system spontaneously—and at least once in the remote past. How life originated is discussed below. Yet no evidence for spontaneous generation now can be cited. Spontaneous generation, also called abiogenesis , the hypothetical process by which living organisms develop from nonliving matter, must be rejected. According to this theory, pieces of cheese and bread wrapped in rags and left in a dark corner were thought to produce mice, because after several weeks mice appeared in the rags. Many believed in spontaneous generation because it explained such occurrences as maggots swarming on decaying meat.

By the 18th century it had become obvious that plants and animals could not be produced by nonliving material. The origin of microorganisms such as yeast and bacteria, however, was not fully determined until French chemist Louis Pasteur proved in the 19th century that microorganisms reproduce, that all organisms come from preexisting organisms, and that all cells come from preexisting cells. Then what evidence is there for the earliest life on Earth?

Past time on Earth, as inferred from the rock record, is divided into four immense periods of time called eons. These are the Hadean (4.6 billion to 4 billion years ago), the Archean (4 billion to 2.5 billion years ago), the Proterozoic (2.5 billion to 541 million years ago), and the Phanerozoic (541 million years ago to the present). For the Hadean Eon, the only record comes from meteorites and lunar rocks. No rocks of Hadean age survive on Earth. In the figure , eons are divided into eras, periods, and epochs. Such entries in the geologic time scale are often called “geologic time intervals.”

Among the oldest known fossils are those found in the Fig Tree Chert from the Transvaal, dated over three billion years ago. These organisms have been identified as bacteria, including oxygenic photosynthetic bacteria (cyanobacteria)—i.e., prokaryotes rather than eukaryotes. Even prokaryotes, however, are exceedingly complicated organisms that grow and reproduce efficiently. Structures of communities of microorganisms, layered rocks called stromatolites , are found from more than three billion years ago. Since Earth is about 4.6 billion years old, these finds suggest that the origin of life must have occurred within a few hundred million years of that time.

Chemical analyses on organic matter extracted from the oldest sediments show what sorts of organic molecules are preserved in the rock record. Porphyrins have been identified in the oldest sediments, as have the isoprenoid derivatives pristane and phytane, breakdown products of cell lipids. Indications that these organic molecules dating from 3.1 billion to 2 billion years ago are of biological origin include the fact that their long-chain hydrocarbons show a preference for a straight-chain geometry. Chemical and physical processes alone tend to produce a much larger proportion of branched-chain and cyclic hydrocarbon molecular geometries than those found in ancient sediments. Nonbiological processes tend to form equal amounts of long-chain carbon compounds with odd and even numbers of carbon atoms. But products of undoubted biological origin, including the oldest sediments, show a distinct preference for odd numbers of carbon atoms per molecule . Another chemical sign of life is an enrichment in the carbon isotope C 12 , which is difficult to account for by nonbiological processes and which has been documented in some of the oldest sediments. This evidence suggests that bacterial photosynthesis or methanogenesis, processes that concentrate C 12 preferentially to C 13 , were present in the early Archean Eon.

The Proterozoic Eon, once thought to be devoid of fossil evidence for life, is now known to be populated by overwhelming numbers of various kinds of bacteria and protist fossils—including acritarchs (spherical, robust unidentified fossils) and the entire range of Ediacaran fauna . The Ediacarans—large, enigmatic , and in some cases animal-like extinct life-forms—are probably related to extant protists. Almost 100 species are known from some 30 locations worldwide, primarily sandstone formations. Most Ediacarans, presumed to have languished in sandy seaside locales, probably depended on their internal microbial symbionts (photo- or chemoautotrophs ) for nourishment . No evidence that they were animals exists. In addition to the Ediacarans, acritarchs, and other abundant microfossils, clear evidence for pre-Phanerozoic, or Precambrian, life includes the massive banded-iron formations (BIFs). Most BIFs date from 2.5 billion to 1.8 billion years ago. They are taken as indirect evidence for oxygen-producing, metal-depositing microscopic Proterozoic life. Investigations that use the electron microprobe (an instrument for visualizing structure and chemical composition simultaneously) and other micropaleontological techniques unfamiliar to classical geology have been employed to put together a much more complete picture of pre-Phanerozoic life.

The earliest fossils are all of aquatic forms. Not until about two billion years ago are cyanobacterial filaments seen that colonized wet soil . By the dawn of the Phanerozoic Eon, life had insinuated itself between the Sun and Earth, both on land and in the waters of the world. For example, the major groups of marine animals such as mollusks and arthropods appeared for the first time about 541 million years ago at the base of the Cambrian Period of the Phanerozoic Eon. Plants and fungi appeared together in the exceptionally well-preserved Rhynie Chert of Scotland, dated about 408 million–360 million years ago in the Devonian Period . Solar energy was diverted to life’s own uses. The biota contrived more and more ways of exploiting more and more environments . Many lineages became extinct. Others persisted and changed. The biosphere’s height and depth increased, as did, by implication , the density of living matter. The proliferation and extinctions of a growing array of life-forms left indelible marks in the sedimentary rocks of the biosphere ( see evolution: The concept of natural selection ).

The origin of life on Earth, explained

The origin of life on Earth stands as one of the great mysteries of science. Various answers have been proposed, all of which remain unverified. To find out if we are alone in the galaxy, we will need to better understand what geochemical conditions nurtured the first life forms. What water, chemistry and temperature cycles fostered the chemical reactions that allowed life to emerge on our planet? Because life arose in the largely unknown surface conditions of Earth’s early history, answering these and other questions remains a challenge.

Several seminal experiments in this topic have been conducted at the University of Chicago, including the Miller-Urey experiment that suggested how the building blocks of life could form in a primordial soup.

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• When did life on Earth begin?

Where did life on Earth begin?

What are the ingredients of life on earth, what are the major scientific theories for how life emerged, what is chirality and why is it biologically important, what research are uchicago scientists currently conducting on the origins of life, when did life on earth begin .

Earth is about 4.5 billion years old. Scientists think that by 4.3 billion years ago, Earth may have developed conditions suitable to support life. The oldest known fossils, however, are only 3.7 billion years old. During that 600 million-year window, life may have emerged repeatedly, only to be snuffed out by catastrophic collisions with asteroids and comets.

The details of those early events are not well preserved in Earth’s oldest rocks. Some hints come from the oldest zircons, highly durable minerals that formed in magma. Scientists have found traces of a form of carbon—an important element in living organisms— in one such 4.1 billion-year-old zircon . However, it does not provide enough evidence to prove life’s existence at that early date.

Two possibilities are in volcanically active hydrothermal environments on land and at sea.

Some microorganisms thrive in the scalding, highly acidic hot springs environments like those found today in Iceland, Norway and Yellowstone National Park. The same goes for deep-sea hydrothermal vents. These chimney-like vents form where seawater comes into contact with magma on the ocean floor, resulting in streams of superheated plumes. The microorganisms that live near such plumes have led some scientists to suggest them as the birthplaces of Earth’s first life forms.

Organic molecules may also have formed in certain types of clay minerals that could have offered favorable conditions for protection and preservation. This could have happened on Earth during its early history, or on comets and asteroids that later brought them to Earth in collisions. This would suggest that the same process could have seeded life on planets elsewhere in the universe.

The recipe consists of a steady energy source, organic compounds and water.

Sunlight provides the energy source at the surface, which drives photosynthesis. On the ocean floor, geothermal energy supplies the chemical nutrients that organisms need to live.

Also crucial are the elements important to life . For us, these are carbon, hydrogen, oxygen, nitrogen, and phosphorus. But there are several scientific mysteries about how these elements wound up together on Earth. For example, scientists would not expect a planet that formed so close to the sun to naturally incorporate carbon and nitrogen. These elements become solid only under very cold temperatures, such as exist in the outer solar system, not nearer to the sun where Earth is. Also, carbon, like gold, is rare at the Earth’s surface. That’s because carbon chemically bonds more often with iron than rock. Gold also bonds more often with metal, so most of it ends up in the Earth’s core. So, how did the small amounts found at the surface get there? Could a similar process also have unfolded on other planets?

The last ingredient is water. Water now covers about 70% of Earth’s surface, but how much sat on the surface 4 billion years ago? Like carbon and nitrogen, water is much more likely to become a part of solid objects that formed at a greater distance from the sun. To explain its presence on Earth, one theory proposes that a class of meteorites called carbonaceous chondrites formed far enough from the sun to have served as a water-delivery system.

There are several theories for how life came to be on Earth. These include:

Life emerged from a primordial soup

As a University of Chicago graduate student in 1952, Stanley Miller performed a famous experiment with Harold Urey, a Nobel laureate in chemistry. Their results explored the idea that life formed in a primordial soup.

Miller and Urey injected ammonia, methane and water vapor into an enclosed glass container to simulate what were then believed to be the conditions of Earth’s early atmosphere. Then they passed electrical sparks through the container to simulate lightning. Amino acids, the building blocks of proteins, soon formed. Miller and Urey realized that this process could have paved the way for the molecules needed to produce life.

Scientists now believe that Earth’s early atmosphere had a different chemical makeup from Miller and Urey’s recipe. Even so, the experiment gave rise to a new scientific field called prebiotic or abiotic chemistry, the chemistry that preceded the origin of life. This is the opposite of biogenesis, the idea that only a living organism can beget another living organism.

Seeded by comets or meteors

Some scientists think that some of the molecules important to life may be produced outside the Earth. Instead, they suggest that these ingredients came from meteorites or comets.

“A colleague once told me, ‘It’s a lot easier to build a house out of Legos when they’re falling from the sky,’” said Fred Ciesla, a geophysical sciences professor at UChicago. Ciesla and that colleague, Scott Sandford of the NASA Ames Research Center, published research showing that complex organic compounds were readily produced under conditions that likely prevailed in the early solar system when many meteorites formed.

Meteorites then might have served as the cosmic Mayflowers that transported molecular seeds to Earth. In 1969, the Murchison meteorite that fell in Australia contained dozens of different amino acids—the building blocks of life.

Comets may also have offered a ride to Earth-bound hitchhiking molecules, according to experimental results published in 2001 by a team of researchers from Argonne National Laboratory, the University of California Berkeley, and Lawrence Berkeley National Laboratory. By showing that amino acids could survive a fiery comet collision with Earth, the team bolstered the idea that life’s raw materials came from space.

In 2019, a team of researchers in France and Italy reported finding extraterrestrial organic material preserved in the 3.3 billion-year-old sediments of Barberton, South Africa. The team suggested micrometeorites as the material’s likely source. Further such evidence came in 2022 from samples of asteroid Ryugu returned to Earth by Japan’s Hayabusa2 mission. The count of amino acids found in the Ryugu samples now exceeds 20 different types .

In 1953, UChicago researchers published a landmark paper in the Journal of Biological Chemistry that marked the discovery of the pro-chirality concept , which pervades modern chemistry and biology. The paper described an experiment showing that the chirality of molecules—or “handedness,” much the way the right and left hands differ from one another—drives all life processes. Without chirality, large biological molecules such as proteins would be unable to form structures that could be reproduced.

Today, research on the origin of life at UChicago is expanding. As scientists have been able to find more and more exoplanets—that is, planets around stars elsewhere in the galaxy—the question of what the essential ingredients for life are and how to look for signs of them has heated up.

Nobel laureate Jack Szostak joined the UChicago faculty as University Professor in Chemistry in 2022 and will lead the University’s new interdisciplinary Origins of Life Initiative to coordinate research efforts into the origin of life on Earth. Scientists from several departments of the Physical Sciences Division are joining the initiative, including specialists in chemistry, astronomy, geology and geophysics.

“Right now we are getting truly unprecedented amounts of data coming in: Missions like Hayabusa and OSIRIS-REx are bringing us pieces of asteroids, which helps us understand the conditions that form planets, and NASA’s new JWST telescope is taking astounding data on the solar system and the planets around us ,” said Prof. Ciesla. “I think we’re going to make huge progress on this question.”

Last updated Sept. 19, 2022.

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There’s no planet B

The scientific evidence is clear: the only celestial body that can support us is the one we evolved with. here’s why.

by Arwen E Nicholson & Raphaëlle D Haywood   + BIO

At the start of the 22nd century, humanity left Earth for the stars. The enormous ecological and climatic devastation that had characterised the last 100 years had led to a world barren and inhospitable; we had used up Earth entirely. Rapid melting of ice caused the seas to rise, swallowing cities whole. Deforestation ravaged forests around the globe, causing widespread destruction and loss of life. All the while, we continued to burn the fossil fuels we knew to be poisoning us, and thus created a world no longer fit for our survival. And so we set our sights beyond Earth’s horizons to a new world, a place to begin again on a planet as yet untouched. But where are we going? What are our chances of finding the elusive planet B, an Earth-like world ready and waiting to welcome and shelter humanity from the chaos we created on the planet that brought us into being? We built powerful astronomical telescopes to search the skies for planets resembling our own, and very quickly found hundreds of Earth twins orbiting distant stars. Our home was not so unique after all. The universe is full of Earths!

This futuristic dream-like scenario is being sold to us as a real scientific possibility, with billionaires planning to move humanity to Mars in the near future. For decades, children have grown up with the daring movie adventures of intergalactic explorers and the untold habitable worlds they find. Many of the highest-grossing films are set on fictional planets, with paid advisors keeping the science ‘realistic’. At the same time, narratives of humans trying to survive on a post-apocalyptic Earth have also become mainstream.

Given all our technological advances, it’s tempting to believe we are approaching an age of interplanetary colonisation. But can we really leave Earth and all our worries behind? No. All these stories are missing what makes a planet habitable to us . What Earth-like means in astronomy textbooks and what it means to someone considering their survival prospects on a distant world are two vastly different things. We don’t just need a planet roughly the same size and temperature as Earth; we need a planet that spent billions of years evolving with us. We depend completely on the billions of other living organisms that make up Earth’s biosphere. Without them, we cannot survive. Astronomical observations and Earth’s geological record are clear: the only planet that can support us is the one we evolved with. There is no plan B. There is no planet B. Our future is here, and it doesn’t have to mean we’re doomed.

D eep down, we know this from instinct: we are happiest when immersed in our natural environment. There are countless examples of the healing power of spending time in nature . Numerous articles speak of the benefits of ‘forest bathing’; spending time in the woods has been scientifically shown to reduce stress, anxiety and depression, and to improve sleep quality, thus nurturing both our physical and mental health. Our bodies instinctively know what we need: the thriving and unique biosphere that we have co-evolved with, that exists only here, on our home planet.

There is no planet B. These days, everyone is throwing around this catchy slogan. Most of us have seen it inscribed on an activist’s homemade placard, or heard it from a world leader. In 2014, the United Nations’ then secretary general Ban Ki-moon said: ‘There is no plan B because we do not have [a] planet B.’ The French president Emmanuel Macron echoed him in 2018 in his historical address to US Congress. There’s even a book named after it. The slogan gives strong impetus to address our planetary crisis. However, no one actually explains why there isn’t another planet we could live on, even though the evidence from Earth sciences and astronomy is clear. Gathering this observation-based information is essential to counter an increasingly popular but flawed narrative that the only way to ensure our survival is to colonise other planets.

The best-case scenario for terraforming Mars leaves us with an atmosphere we are incapable of breathing

The most common target of such speculative dreaming is our neighbour Mars. It is about half the size of Earth and receives about 40 per cent of the heat that we get from the Sun. From an astronomer’s perspective, Mars is Earth’s identical twin. And Mars has been in the news a lot lately, promoted as a possible outpost for humanity in the near future . While human-led missions to Mars seem likely in the coming decades, what are our prospects of long-term habitation on Mars? Present-day Mars is a cold, dry world with a very thin atmosphere and global dust storms that can last for weeks on end. Its average surface pressure is less than 1 per cent of Earth’s. Surviving without a pressure suit in such an environment is impossible. The dusty air mostly consists of carbon dioxide (CO 2 ) and the surface temperature ranges from a balmy 30ºC (86ºF) in the summer, down to -140ºC (-220ºF) in the winter; these extreme temperature changes are due to the thin atmosphere on Mars.

Despite these clear challenges, proposals for terraforming Mars into a world suitable for long-term human habitation abound. Mars is further from the Sun than Earth, so it would require significantly more greenhouse gases to achieve a temperature similar to Earth’s. Thickening the atmosphere by releasing CO 2 in the Martian surface is the most popular ‘solution’ to the thin atmosphere on Mars. However, every suggested method of releasing the carbon stored in Mars requires technology and resources far beyond what we are currently capable of. What’s more, a recent NASA study determined that there isn’t even enough CO 2 on Mars to warm it sufficiently.

Even if we could find enough CO 2 , we would still be left with an atmosphere we couldn’t breathe. Earth’s atmosphere contains only 0.04 per cent CO 2 , and we cannot tolerate an atmosphere high in CO 2 . For an atmosphere with Earth’s atmospheric pressure, CO 2 levels as high as 1 per cent can cause drowsiness in humans, and once we reach levels of 10 per cent CO 2 , we will suffocate even if there is abundant oxygen. The proposed absolute best-case scenario for terraforming Mars leaves us with an atmosphere we are incapable of breathing; and achieving it is well beyond our current technological and economic capabilities.

Instead of changing the atmosphere of Mars, a more realistic scenario might be to build habitat domes on its surface with internal conditions suitable for our survival. However, there would be a large pressure difference between the inside of the habitat and the outside atmosphere. Any breach in the habitat would rapidly lead to depressurisation as the breathable air escapes into the thin Martian atmosphere. Any humans living on Mars would have to be on constant high alert for any damage to their building structures, and suffocation would be a daily threat.

F rom an astronomical perspective, Mars is Earth’s twin; and yet, it would take vast resources, time and effort to transform it into a world that wouldn’t be capable of providing even the bare minimum of what we have on Earth. Suggesting that another planet could become an escape from our problems on Earth suddenly seems absurd. But are we being pessimistic? Do we just need to look further afield?

Next time you are out on a clear night, look up at the stars and choose one – you are more likely than not to pick one that hosts planets. Astronomical observations today confirm our age-old suspicion that all stars have their own planetary systems. As astronomers, we call these exoplanets. What are exoplanets like? Could we make any of them our home?

The majority of exoplanets discovered to date were found by NASA’s Kepler mission, which monitored the brightness of 100,000 stars over four years, looking for dips in a star’s light as a planet obscures it each time it completes an orbit around it.

The solar system associated with star Kepler-90 has a similar configuration to our solar system with small planets found orbiting close to their star, and the larger planets found farther away. Courtesy NASA/Ames /Wendy Stenzel

Kepler observed more than 900 Earth-sized planets with a radius up to 1.25 times that of our world. These planets could be rocky (for the majority of them, we haven’t yet determined their mass, so we can only make this inference based on empirical relations between planetary mass and radius). Of these 900 or so Earth-sized planets, 23 are in the habitable zone. The habitable zone is the range of orbits around a star where a planet can be considered temperate : the planet’s surface can support liquid water (provided there is sufficient atmospheric pressure), a key ingredient of life as we know it. The concept of the habitable zone is very useful because it depends on just two astrophysical parameters that are relatively easy to measure: the distance of the planet to its parent star, and the star’s temperature. It’s worth keeping in mind that the astronomical habitable zone is a very simple concept and, in reality, there are many more factors at play in the emergence of life; for example, this concept does not consider plate tectonics , which are thought to be crucial to sustain life on Earth.

Planets with similar observable properties to Earth are very common: at least one in 10 stars hosts them

How many Earth-sized, temperate planets are there in our galaxy? Since we have discovered only a handful of these planets so far, it is still quite difficult to estimate their number. Current estimates of the frequency of Earth-sized planets rely on extrapolating measured occurrence rates of planets that are slightly bigger and closer to their parent star, as those are easier to detect. The studies are primarily based on observations from the Kepler mission, which surveyed more than 100,000 stars in a systematic fashion. These stars are all located in a tiny portion of the entire sky; so, occurrence rate studies assume that this part of the sky is representative of the full galaxy. These are all reasonable assumptions for the back-of-the-envelope estimate that we are about to make.

Several different teams carried out their own analyses and, on average, they found that roughly one in three stars (30 per cent) hosts an Earth-sized, temperate planet. The most pessimistic studies found a rate of 9 per cent, which is about one in 10 stars, and the studies with the most optimistic results found that virtually all stars host at least one Earth-sized, temperate planet, and potentially even several of them.

At first sight, this looks like a huge range in values; but it’s worth taking a step back and realising that we had absolutely no constraints whatsoever on this number just 20 years ago. Whether there are other planets similar to Earth is a question that we’ve been asking for millennia, and this is the very first time that we are able to answer it based on actual observations. Before the Kepler mission, we had no idea whether we would find Earth-sized, temperate planets around one in 10, or one in a million stars. Now we know that planets with similar observable properties to Earth are very common: at least one in 10 stars hosts these kinds of planets.

An artist’s concept shows exoplanet Kepler-1649c orbiting around its host red dwarf star. Courttesy NASA/Ames

Let’s now use these numbers to predict the number of Earth-sized, temperate planets in our entire galaxy. For this, let’s take the average estimate of 30 per cent, or roughly one in three stars. Our galaxy hosts approximately 300 billion stars, which adds up to 90 billion roughly Earth-sized, roughly temperate planets. This is a huge number, and it can be very tempting to think that at least one of these is bound to look exactly like Earth.

One issue to consider is that other worlds are at unimaginable distances from us. Our neighbour Mars is on average 225 million kilometres (about 140 million miles) away. Imagine a team of astronauts travelling in a vehicle similar to NASA’s robotic New Horizons probe, one of humankind’s fastest spacecrafts – which flew by Pluto in 2015. With New Horizons’ top speed of around 58,000 kph, it would take at least 162 days to reach Mars. Beyond our solar system, the closest star to us is Proxima Centauri, at a distance of 40 trillion kilometres. Going in the same space vehicle, it would take our astronaut crew 79,000 years to reach planets that might exist around our nearest stellar neighbour.

S till, let’s for a moment optimistically imagine that we find a perfect Earth twin: a planet that really is exactly like Earth. Let’s imagine that some futuristic form of technology exists, ready to whisk us away to this new paradise. Keen to explore our new home, we eagerly board our rocket, but on landing we soon feel uneasy. Where is the land? Why is the ocean green and not blue? Why is the sky orange and thick with haze? Why are our instruments detecting no oxygen in the atmosphere? Was this not supposed to be a perfect twin of Earth?

As it turns out, we have landed on a perfect twin of the Archean Earth, the aeon during which life first emerged on our home world. This new planet is certainly habitable: lifeforms are floating around the green, iron-rich oceans, breathing out methane that is giving the sky that unsettling hazy, orange colour. This planet sure is habitable – just not to us . It has a thriving biosphere with plenty of life, but not life like ours. In fact, we would have been unable to survive on Earth for around 90 per cent of its history; the oxygen-rich atmosphere that we depend on is a recent feature of our planet.

The earliest part of our planet’s history, known as the Hadean aeon, begins with the formation of the Earth. Named after the Greek underworld due to our planet’s fiery beginnings, the early Hadean would have been a terrible place with molten lava oceans and an atmosphere of vaporised rock. Next came the Archean aeon, beginning 4 billion years ago, when the first life on Earth flourished. But, as we just saw, the Archean would be no home for a human. The world where our earliest ancestors thrived would kill us in an instant. After the Archean came the Proterozoic, 2.5 billion years ago. In this aeon, there was land, and a more familiar blue ocean and sky. What’s more, oxygen finally began to accumulate in the atmosphere. But let’s not get too excited: the level of oxygen was less than 10 per cent of what we have today. The air would still have been impossible for us to breathe. This time also experienced global glaciation events known as snowball Earths, where ice covered the globe from poles to equator for millions of years at a time. Earth has spent more of its time fully frozen than the length of time that we humans have existed.

We would have been incapable of living on our planet for most of its existence

Earth’s current aeon, the Phanerozoic, began only around 541 million years ago with the Cambrian explosion – a period of time when life rapidly diversified. A plethora of life including the first land plants, dinosaurs and the first flowering plants all appeared during this aeon. It is only within this aeon that our atmosphere became one that we can actually breathe. This aeon has also been characterised by multiple mass extinction events that wiped out as much as 90 per cent of all species over short periods of time. The factors that brought on such devastation are thought to be a combination of large asteroid impacts, and volcanic, chemical and climate changes occurring on Earth at the time. From the point of view of our planet, the changes leading to these mass extinctions are relatively minor. However, for lifeforms at the time, such changes shattered their world and very often led to their complete extinction.

Looking at Earth’s long history, we find that we would have been incapable of living on our planet for most of its existence. Anatomically modern humans emerged less than 400,000 years ago; we have been around for less than 0.01 per cent of the Earth’s story. The only reason we find Earth habitable now is because of the vast and diverse biosphere that has for hundreds of millions of years evolved with and shaped our planet into the home we know today. Our continued survival depends on the continuation of Earth’s present state without any nasty bumps along the way. We are complex lifeforms with complex needs. We are entirely dependent on other organisms for all our food and the very air we breathe. The collapse of Earth’s ecosystems is the collapse of our life-support systems. Replicating everything Earth offers us on another planet, on timescales of a few human lifespans, is simply impossible.

Some argue that we need to colonise other planets to ensure the future of the human race. In 5 billion years, our Sun, a middle-aged star, will become a red giant, expanding in size and possibly engulfing Earth. In 1 billion years, the gradual warming of our Sun is predicted to cause Earth’s oceans to boil away. While this certainly sounds worrying, 1 billion years is a long, long time. A billion years ago, Earth’s landmasses formed the supercontinent Rodinia, and life on Earth consisted in single-celled and small multicellular organisms. No plants or animals yet existed. The oldest Homo sapiens remains date from 315,000 years ago, and until 12,000 years ago all humans lived as hunter-gatherers.

The industrial revolution happened less than 500 years ago. Since then, human activity in burning fossil fuels has been rapidly changing the climate, threatening human lives and damaging ecosystems across the globe. Without rapid action, human-caused climate change is predicted to have devastating global consequences within the next 50 years. This is the looming crisis that humanity must focus on. If we can’t learn to work within the planetary system that we evolved with, how do we ever hope to replicate these deep processes on another planet? Considering how different human civilisations are today from even 5,000 years ago, worrying about a problem that humans may have to tackle in a billion years is simply absurd. It would be far simpler to go back in time and ask the ancient Egyptians to invent the internet there and then. It’s also worth considering that many of the attitudes towards space colonisation are worryingly close to the same exploitative attitudes that have led us to the climate crisis we now face.

Earth is the home we know and love not because it is Earth-sized and temperate. No, we call this planet our home thanks to its billion-year-old relationship with life. Just as people are shaped not only by their genetics, but by their culture and relationships with others, planets are shaped by the living organisms that emerge and thrive on them. Over time, Earth has been dramatically transformed by life into a world where we, humans, can prosper. The relationship works both ways: while life shapes its planet, the planet shapes its life. Present-day Earth is our life-support system, and we cannot live without it.

While Earth is currently our only example of a living planet, it is now within our technological reach to potentially find signs of life on other worlds. In the coming decades, we will likely answer the age-old question: are we alone in the Universe? Finding evidence for alien life promises to shake the foundations of our understanding of our own place in the cosmos. But finding alien life does not mean finding another planet that we can move to. Just as life on Earth has evolved with our planet over billions of years, forming a deep, unique relationship that makes the world we see today, any alien life on a distant planet will have a similarly deep and unique bond with its own planet. We can’t expect to be able to crash the party and find a warm welcome.

Living on a warming Earth presents many challenges. But these pale in comparison with the challenges of converting Mars, or any other planet, into a viable alternative. Scientists study Mars and other planets to better understand how Earth and life formed and evolved, and how they shape each other. We look to worlds beyond our horizons to better understand ourselves. In searching the Universe, we are not looking for an escape to our problems: Earth is our unique and only home in the cosmos. There is no planet B.

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Essay on Earth: Check Samples for 100, 300 Words

• Updated on  
• Sep 27, 2023

Essay on Earth: Earth, our cherished celestial abode, is a marvel of the cosmos. It teems with life, boasts breathtaking landscapes, and endures the test of time. In this blog, we embark on a journey to explore the myriad facets of our planet, from its geological mysteries to the pressing challenges of preserving its ecological harmony.

Table of Contents

• 1 Earth’s Geological History
• 2 Earth’s Climate
• 3 Preserving Earth’s Sustainability
• 4 Sample Essay On Earth In 100 Words
• 5 Sample Essay On Earth In 300 Words

Earth’s Geological History

Earth’s geological history spans eons, an epic tale told through rocks, fossils, and continents. It begins with the formation of our planet over 4.5 billion years ago, a violent birth amidst cosmic chaos. For billions of years, Earth underwent tumultuous transformations, from the fiery hell of its early years to the emergence of oceans and continents. 

Over time, life took root, evolving from simple organisms into the diverse array we know today. Plate tectonics, volcanic eruptions, and meteor impacts further shaped our world. Understanding Earth’s geological history not only unveils its past but also offers insights into its future and the importance of conservation.

Must Read: Essay On Waste Management

Earth’s Climate

Earth’s climate is a complex interplay of atmospheric and oceanic dynamics that determine its weather patterns and long-term conditions. It encompasses a delicate balance of temperature, precipitation, and atmospheric composition, shaping the environments where life thrives. However, this equilibrium is now disrupted by human-induced climate change.

Human activities, primarily the burning of fossil fuels and deforestation, release greenhouse gases into the atmosphere, trapping heat and causing global temperatures to rise. This shift is causing extreme weather events, rising sea levels, and disrupting ecosystems worldwide. Addressing this climate crisis is one of the most pressing challenges of our time, requiring collective action to mitigate its impacts.

Preserving Earth’s Sustainability

Sustainability on Earth is the pivotal concept guiding our actions toward a harmonious coexistence with the planet. It revolves around responsible resource management, reducing waste, and respecting ecological limits. Sustainable practices encompass clean energy, conservation of biodiversity, and equitable access to resources, ensuring a resilient future.

Achieving sustainability is paramount in mitigating environmental crises, such as climate change and habitat loss. It demands global cooperation, conscious consumer choices, and innovative solutions. By embracing sustainability, we safeguard Earth’s precious ecosystems, secure resources for future generations, and preserve the beauty and diversity of our irreplaceable home.

Sample Essay On Earth In 100 Words

Earth, our celestial home, is a testament to the grandeur of the cosmos. For over 4.5 billion years, it has nurtured life, from the simplest organisms to the diverse tapestry we witness today. Earth’s geological history reveals eons of transformation, while its climate sustains ecosystems across continents. However, our planet faces unprecedented challenges. Human actions, from pollution to deforestation, imperil the delicate balance of nature. The climate crisis threatens ecosystems and communities. Yet, Earth’s resilience offers hope. Through conservation, sustainable practices, and global cooperation, we can safeguard this precious orb, ensuring its enduring beauty for generations to come.

Must Read: Essay On Save Water 

Sample Essay On Earth In 300 Words

Earth, our celestial abode, stands as a testament to the sublime beauty and intricate complexity of the cosmos. One of Earth’s most captivating aspects is its geological history, a narrative etched in the layers of rock, sediment, and fossils. From its tumultuous birth in a maelstrom of cosmic debris, our planet has evolved through epochs of geological transformation. Continents have shifted, mountain ranges have risen and eroded, and life has thrived and adapted. Exploring Earth’s geological history is like reading a captivating story, revealing the secrets of its past and the forces that have shaped its present landscapes.

Yet, Earth’s allure extends far beyond its geological marvels. Its climate, a symphony of atmospheric and oceanic interactions, creates diverse ecosystems that span the globe. From the lush rainforests of the Amazon to the stark beauty of polar ice caps, Earth’s climate has sculpted environments that support a dazzling array of life forms. The rhythm of seasons, the dance of wind and water, and the harmony of predator and prey are all part of this intricate tapestry.

However, as we celebrate Earth’s wonders, we must also confront the pressing challenges it faces today. Human activities, driven by industry and consumption, have led to environmental degradation on an unprecedented scale. Pollution chokes our air and water, while deforestation and habitat loss threaten countless species. Perhaps the most urgent challenge is the spectre of climate change, driven by the relentless emission of greenhouse gases. Rising temperatures, extreme weather events, and melting ice caps are stark reminders of the consequences.

Yet, in the face of these challenges, Earth displays its resilience. It offers hope that, through collective effort, we can restore the balance that sustains life. Conservation, sustainable practices, and international cooperation are the tools we possess to safeguard our cherished home. In conclusion, Earth is a treasure trove of geological wonders and ecological diversity.

Earth is called a “blue planet” because its surface is 70% water, giving it a predominantly blue appearance when seen from space.

Earth’s resources are depleting due to overexploitation, pollution, and unsustainable practices, threatening ecosystems, freshwater, minerals, and fossil fuels.

Write about Earth’s beauty, biodiversity, ecological balance, human impact, and the urgent need for conservation and sustainable practices.

We hope this blog gave you an idea about how to write and present an essay on Earth that puts forth your opinions. The skill of writing an essay comes in handy when appearing for standardized language tests. Thinking of taking one soon? Leverage Edu provides the best online test prep for the same via Leverage Live . Register today to know more!

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September 1, 2009

13 min read

The Origin of Life on Earth

Fresh clues hint at how the first living organisms arose from inanimate matter

By Alonso Ricardo & Jack W. Szostak

Every living cell, even the simplest bacterium, teems with molecular contraptions that would be the envy of any nanotechnologist. As they incessantly shake or spin or crawl around the cell, these machines cut, paste and copy genetic molecules, shuttle nutrients around or turn them into energy, build and repair cellular membranes, relay mechanical, chemical or electrical messages—the list goes on and on, and new discoveries add to it all the time.

It is virtually impossible to imagine how a cell’s machines, which are mostly protein-based catalysts called enzymes, could have formed spontaneously as life first arose from nonliving matter around 3.7 billion years ago. To be sure, under the right conditions some building blocks of proteins, the amino acids, form easily from simpler chemicals, as Stanley L. Miller and Harold C. Urey of the University of Chicago discovered in pioneering experiments in the 1950s. But going from there to proteins and enzymes is a different matter.

A cell’s protein-making process involves complex enzymes pulling apart the strands of DNA’s double helix to extract the information contained in genes (the blueprints for the proteins) and translate it into the finished product. Thus, explaining how life began entails a serious paradox: it seems that it takes proteins—as well as the information now stored in DNA—to make proteins.

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On the other hand, the paradox would disappear if the first organisms did not require proteins at all. Recent experiments suggest it would have been possible for genetic molecules similar to DNA or to its close relative RNA to form spontaneously. And because these molecules can curl up in different shapes and act as rudimentary catalysts, they may have become able to copy themselves—to reproduce—without the need for proteins. The earliest forms of life could have been simple membranes made of fatty acids—also structures known to form spontaneously—that enveloped water and these self-replicating genetic molecules. The genetic material would encode the traits that each generation handed down to the next, just as DNA does in all things that are alive today. Fortuitous mutations, appearing at random in the copying process, would then propel evolution, enabling these early cells to adapt to their environment, to compete with one another, and eventually to turn into the life-forms we know.

The actual nature of the first organisms and the exact circumstances of the origin of life may be forever lost to science. But research can at least help us understand what is possible. The ultimate challenge is to construct an artificial organism that can reproduce and evolve. Creating life anew will certainly help us understand how life can start, how likely it is that it exists on other worlds and, ultimately, what life is.

Got to Start Somewhere One of the most difficult and interesting mysteries surrounding the origin of life is exactly how the genetic material could have formed starting from simpler molecules present on the early earth. Judging from the roles that RNA has in modern cells, it seems likely that RNA appeared before DNA. When modern cells make proteins, they first copy genes from DNA into RNA and then use the RNA as a blueprint to make proteins. This last stage could have existed independently at first. Later on, DNA could have ap­­peared as a more permanent form of storage, thanks to its superior chemical stability.

Investigators have one more reason for thinking that RNA came before DNA. The RNA versions of enzymes, called ribozymes, also serve a pivotal role in modern cells. The structures that translate RNA into proteins are hybrid RNA-protein machines, and it is the RNA in them that does the catalytic work. Thus, each of our cells appears to carry in its ribosomes “fossil” evidence of a primordial RNA world.

Much research, therefore, has focused on understanding the possible origin of RNA. Genetic molecules such as DNA and RNA are polymers (strings of smaller molecules) made of building blocks called nucleotides. In turn, nucleotides have three distinct components: a sugar, a phosphate and a nucleobase. Nucleobases come in four types and constitute the alphabet in which the polymer encodes information. In a DNA nucleotide the nucleobase can be A, G, C or T, standing for the molecules adenine, guanine, cytosine or thymine; in the RNA alphabet the letter U, for uracil, replaces the T. The nucleobases are nitrogen-rich compounds that bind to one another according to a simple rule; thus, A pairs with U (or T), and G pairs with C. Such base pairs form the rungs of DNA’s twisted ladder—the familiar double helix—and their exclusive pairings are crucial for faithfully copying the information so a cell can reproduce. Meanwhile the phosphate and sugar molecules form the backbone of each strand of DNA or RNA.

Nucleobases can assemble spontaneously, in a series of steps, from cyanide, acetylene and water—simple molecules that were certainly present in the primordial mix of chemicals. Sugars are also easy to assemble from simple starting materials. It has been known for well over 100 years that mixtures of many types of sugar molecules can be obtained by warming an alkaline solution of formaldehyde, which also would have been available on the young planet. The problem, however, is how to obtain the “right” kind of sugar—ribose, in the case of RNA—to make nucleotides. Ribose, along with three closely related sugars, can form from the reaction of two simpler sugars that contain two and three carbon atoms, respectively. Ribose’s ability to form in that way does not solve the problem of how it became abundant on the early earth, however, because it turns out that ribose is unstable and rapidly breaks down in an even mildly alkaline solution. In the past, this observation has led many researchers to conclude that the first genetic molecules could not have contained ribose. But one of us (Ricardo) and others have discovered ways in which ribose could have been stabilized.

The phosphate part of nucleotides presents another intriguing puzzle. Phosphorus—the central element of the phosphate group—is abundant in the earth’s crust but mostly in minerals that do not dissolve readily in water, where life presumably originated. So it is not obvious how phosphates would have gotten into the prebiotic mix. The high temperatures of volcanic vents can convert phosphate-containing minerals to soluble forms of phosphate, but the amounts released, at least near modern volcanoes, are small. A completely different potential source of phosphorus compounds is schreibersite, a mineral commonly found in certain meteors.

In 2005 Matthew Pasek and Dante Lauretta of the University of Arizona discovered that the corrosion of schreibersite in water releases its phosphorus component. This pathway seems promising because it releases phosphorus in a form that is both much more soluble in water than phosphate and much more reactive with organic (carbon-based) compounds.

Some Assembly Required Given that we have at least an outline of potential pathways leading to the nucleobases, sugars and phosphate, the next logical step would be to properly connect these components. This step, however, is the one that has caused the most intense frustration in prebiotic chemistry research for the past several decades. Simply mixing the three components in water does not lead to the spontaneous formation of a nucleotide—largely be­­cause each joining reaction also involves the release of a water molecule, which does not often occur spontaneously in a watery solution. For the needed chemical bonds to form, energy must be supplied, for example, by adding energy-rich compounds that aid in the reaction. Many such compounds may have existed on the early earth. In the laboratory, however, reactions powered by such molecules have proved to be inefficient at best and in most cases completely unsuccessful.

This spring—to the field’s great excitement—John Sutherland and his co-workers at the University of Manchester in England announced that they found a much more plausible way that nucleotides could have formed, which also sidesteps the issue of ribose’s instability. These creative chemists abandoned the tradition of attempting to make nucleotides by joining a nucleobase, sugar and phosphate. Their approach relies on the same simple starting materials employed previously, such as derivatives of cyanide, acetylene and formaldehyde. But instead of forming nucleobase and ribose separately and then trying to join them, the team mixed the start­ing ingredients together, along with phosphate. A complex web of reactions—with phosphate acting as a crucial catalyst at several steps along the way—produced a small molecule called 2-amino­oxazole, which can be viewed as a fragment of a sugar joined to a piece of a nucleobase.

A crucial feature of this small, stable molecule is that it is very volatile. Perhaps small amounts of 2-aminooxazole formed together with a mixture of other chemicals in a pond on the early earth; once the water evaporated, the 2-amino­oxazole vaporized, only to condense elsewhere, in a purified form. There it would accumulate as a reservoir of material, ready for further chemical reactions that would form a full sugar and nucleobase attached to each other.

Another important and satisfying aspect of this chain of reactions is that some of the early-stage by-products facilitate transformations at later stages in of the process. Elegant as it is, the pathway does not generate exclusively the “correct” nucleotides: in some cases, the sugar and nucleobase are not joined in the proper spatial arrangement. But amazingly, exposure to ultraviolet light—intense solar UV rays hit shallow waters on the early earth—destroys the “incorrect” nucleotides and leaves behind the “correct” ones. The end result is a remarkably clean route to the C and U nucleotides. Of course, we still need a route to G and A, so challenges remain. But the work by Sutherland’s team is a major step toward explaining how a molecule as complex as RNA could have formed on the early earth.

Some Warm, Little Vial Once we have nucleotides, the final step in the formation of an RNA molecule is polymerization: the sugar of one nucleotide forms a chemical bond with the phosphate of the next, so that nucleotides string themselves together into a chain. Once again, in water the bonds do not form spontaneously and instead require some external energy. By adding various chemicals to a solution of chemically reactive versions of the nucleotides, researchers have been able to produce short chains of RNA, two to 40 nucleotides long. In the late 1990s Jim Ferris and his co-workers at the Rensselaer Polytechnic Institute showed that clay minerals enhance the process, producing chains of up to 50 or so nucleotides. (A typical gene today is thousands to millions of nucleotides long.) The minerals’ intrinsic ability to bind nucleotides brings reactive molecules close together, thereby facilitating the formation of bonds between them.

The discovery reinforced the suggestion by some researchers that life may have started on mineral surfaces, perhaps in clay-rich muds at the bottom of pools of water formed by hot springs [see “Life's Rocky Start,” by Robert M. Hazen; Scientific American, April 2001].

Certainly finding out how genetic polymers first arose would not by itself solve the problem of the origin of life. To be “alive,” organisms must be able to go forth and multiply—a process that includes copying genetic information. In modern cells enzymes, which are protein-based, carry out this copying function.

But genetic polymers, if they are made of the right sequences of nucleotides, can fold into complex shapes and can catalyze chemical reactions, just as today’s enzymes do. Hence, it seems plausible that RNA in the very first organisms could have directed its own replication. This notion has inspired several experiments, both at our lab and at David Bartel’s lab at the Massachusetts In­stitute of Technology, in which we “evolved” new ribozymes.

We started with trillions of random RNA sequences. Then we selected the ones that had catalytic properties, and we made copies of those. At each round of copying some of the new RNA strands underwent mutations that turned them into more efficient catalysts, and once again we singled those out for the next round of copying. By this directed evolution we were able to produce ribozymes that can catalyze the copying of relatively short strands of other RNAs, although they fall far short of being able to copy polymers with their own sequences into progeny RNAs.

Recently the principle of RNA self-replication received a boost from Tracey Lincoln and Gerald Joyce of the Scripps Research Institute, who evolved two RNA ribozymes, each of which could make copies of the other by joining together two shorter RNA strands. Unfortunately, success in the experiments required the presence of preexisting RNA pieces that were far too long and complex to have accumulated spontaneously. Still, the results suggest that RNA has the raw catalytic power to catalyze its own replication.

Is there a simpler alternative? We and others are now exploring chemical ways of copying genetic molecules without the aid of catalysts. In recent experiments, we started with single, “template” strands of DNA. (We used DNA because it is cheaper and easier to work with, but we could just as well have used RNA.) We mixed the templates in a solution containing isolated nucleotides to see if nucleotides would bind to the template through complementary base pairing (A joining to T and C to G) and then polymerize, thus forming a full double strand. This would be the first step to full replication: once a double strand had formed, separation of the strands would allow the complement to serve as a template for copying the original strand. With standard DNA or RNA, the process is exceedingly slow. But small changes to the chemical structure of the sugar component—changing one oxygen-hydrogen pair to an amino group (made of nitrogen and hydrogen)—made the polymerization hundreds of times faster, so that complementary strands formed in hours instead of weeks. The new polymer behaved much like classic RNA despite having nitrogen-phosphorus bonds instead of the normal oxygen-phosphorus bonds.

Boundary Issues If we assume for the moment that the gaps in our understanding of the chemistry of life’s origin will someday be filled, we can begin to consider how molecules might have interacted to assemble into the first cell-like structures, or “protocells.”

The membranes that envelop all modern cells consist primarily of a lipid bilayer: a double sheet of such oily molecules as phospholipids and cholesterol. Membranes keep a cell’s components physically together and form a barrier to the uncontrolled passage of large molecules. Sophisticated proteins embedded in the membrane act as gatekeepers and pump molecules in and out of the cell, while other proteins assist in the construction and repair of the membrane. How on earth could a rudimentary protocell, lacking protein machinery, carry out these tasks?

Primitive membranes were probably made of simpler molecules, such as fatty acids (which are one component of the more complex phospholipids). Studies in the late 1970s showed that membranes could indeed assemble spontaneously from plain fatty acids, but the general feeling was that these membranes would still pose a formidable barrier to the entry of nucleotides and other complex nutrients into the cell. This notion suggested that cellular metabolism had to develop first, so that cells could synthesize nu­cleotides for themselves. Work in our lab has shown, however, that molecules as large as nucleotides can in fact easily slip across membranes as long as both nucleotides and membranes are simpler, more “primitive” versions of their modern counterparts.

This finding allowed us to carry out a simple experiment modeling the ability of a protocell to copy its genetic information using environmentally supplied nutrients. We prepared fatty acid–based membrane vesicles containing a short piece of single-stranded DNA. As before, the DNA was meant to serve as a template for a new strand. Next, we exposed these vesicles to chemically reactive versions of nucleotides. The nucleotides crossed the membrane spontaneously and, once inside the model protocell, lined up on the DNA strand and reacted with one another to generate a complementary strand. The experiment supports the idea that the first protocells contained RNA (or something similar to it) and little else and replicated their genetic material without enzymes.

Let There Be Division For protocells to start reproducing, they would have had to be able to grow, duplicate their genetic contents and divide into equivalent “daughter” cells. Experiments have shown that primitive vesicles can grow in at least two distinct ways. In pioneering work in the 1990s, Pier Luigi Luisi and his colleagues at the Swiss Federal Institute of Technology in Zurich added fresh fatty acids to the water surrounding such vesicles. In re­­sponse, the membranes incorporated the fatty acids and grew in surface area. As water and dissolved substances slowly entered the interior, the cell’s volume also increased.

A second approach, which was explored in our lab by then graduate student Irene Chen, involved competition between protocells. Model protocells filled with RNA or similar materials became swollen, an osmotic effect resulting from the attempt of water to enter the cell and equalize its concentration inside and outside. The membrane of such swollen vesicles thus came under tension, and this tension drove growth, because adding new molecules relaxes the tension on the membrane, lowering the energy of the system. In fact, swollen vesicles grew by stealing fatty acids from relaxed neighboring vesicles, which shrank.

In the past year Ting Zhu, a graduate student in our lab, has observed the growth of model protocells after feeding them fresh fatty acids. To our amazement, the initially spherical vesicles did not grow simply by getting larger. Instead they first extended a thin filament. Over about half an hour, this protruding filament grew longer and thicker, gradually transforming the entire initial vesicle into a long, thin tube. This structure was quite delicate, and gentle shaking (such as might occur as wind generates waves on a pond) caused it to break into a number of smaller, spherical daughter protocells, which then grew larger and repeated the cycle.

Given the right building blocks, then, the formation of protocells does not seem that difficult: membranes self-assemble, genetic polymers self-assemble, and the two components can be brought together in a variety of ways, for example, if the membranes form around preexisting polymers. These sacs of water and RNA will also grow, absorb new molecules, compete for nutrients, and divide. But to become alive, they would also need to reproduce and evolve. In particular, they need to separate their RNA double strands so each single strand can act as a template for a new double strand that can be handed down to a daughter cell.

This process would not have started on its own, but it could have with a little help. Imagine, for example, a volcanic region on the otherwise cold surface of the early earth (at the time, the sun shone at only 70 percent of its current power). There could be pools of cold water, perhaps partly covered by ice but kept liquid by hot rocks. The temperature differences would cause convection currents, so that every now and then protocells in the water would be exposed to a burst of heat as they passed near the hot rocks, but they would almost instantly cool down again as the heated water mixed with the bulk of the cold water. The sudden heating would cause a double helix to separate into single strands. Once back in the cool region, new double strands—copies of the original one—could form as the single strands acted as templates.

As soon as the environment nudged protocells to start reproducing, evolution kicked in. In particular, at some point some of the RNA sequences mutated, becoming ribozymes that sped up the copying of RNA—thus adding a competitive advantage. Eventually ribozymes began to copy RNA without external help.

It is relatively easy to imagine how RNA-based protocells may have then evolved [see box above]. Metabolism could have arisen gradually, as new ribozymes enabled cells to synthesize nutrients internally from simpler and more abundant starting materials. Next, the organisms might have added protein making to their bag of chemical tricks.

With their astonishing versatility, proteins would have then taken over RNA’s role in assisting genetic copying and metabolism. Later, the organisms would have “learned” to make DNA, gaining the advantage of possessing a more robust carrier of genetic information. At that point, the RNA world became the DNA world, and life as we know it began.

Note: This article was originally printed with the title, "Origin of Life on Earth."

Early Life on Earth – Animal Origins

In the beginning.

Today we take for granted that we live among diverse communities of animals that feed on each other. Our ecosystems are structured by feeding relationships like killer whales eating seals, which eat squid, which feed on krill. These and other animals require oxygen to extract energy from their food. But that’s not how life on Earth used to be.

With an environment devoid of oxygen and high in methane, for much of its history Earth would not have been a welcoming place for animals. The earliest life forms we know of were microscopic organisms (microbes) that left signals of their presence in rocks about 3.7 billion years old. The signals consisted of a type of carbon molecule that is produced by living things.

Evidence of microbes was also preserved in the hard structures (“stromatolites”) they made, which date to 3.5 billion years ago. Stromatolites are created as sticky mats of microbes trap and bind sediments into layers. Minerals precipitate inside the layers, creating durable structures even as the microbes die off. Scientists study today’s, rare living stromatolite reefs to better understand Earth’s earliest life forms.

An Oxygen Atmosphere

When cyanobacteria evolved at least 2.4 billion years ago, they set the stage for a remarkable transformation. They became Earth’s first photo-synthesizers, making food using water and the Sun’s energy, and releasing oxygen as a result. This catalyzed a sudden, dramatic rise in oxygen, making the environment less hospitable for other microbes that could not tolerate oxygen.

Evidence for this Great Oxidation Event is recorded in changes in seafloor rocks called Banded Iron Formations , or BIFs. When shallow water, enriched in oxygen, mixes with deep, iron-rich water, the iron reacts chemically with oxygen (it gets oxidized) and forms iron oxide minerals. These minerals sink down to the seafloor, forming dark, iron-rich layers in the rocks.

After the initial pulse of oxygen, it stabilized at lower levels where it would remain for a couple billion years more. In fact, as cyanobacteria died and drifted down through the water, the decomposition of their bodies probably reduced oxygen levels. So, the ocean was still not a suitable environment for most lifeforms that need ample oxygen.

Multicellular Life

However, other innovations were occurring. While they can process lots of chemicals, microbes did not have the specialized cells that are needed for complex bodies. Animal bodies have various cells – skin, blood, bone – which contain organelles, each doing a distinct job. Microbes are just single cells with no organelles and no nuclei to package their DNA.

Something revolutionary happened as microbes began living inside other microbes, functioning as organelles for them. Mitochondria, the organelles that process food into energy, evolved from these mutually beneficial relationships. Also, for the first time, DNA became packaged in nuclei. The new complex cells (“eukaryotic cells”) boasted specialized parts playing specialized roles that supported the whole cell.

Cells also began living together, probably because certain benefits could be obtained. Groups of cells might be able to feed more efficiently or gain protection from simply being bigger. Living collectively, cells began to support the needs of the group by each cell doing a specific job. Some cells were tasked with making junctions to hold the group together, while other cells made digestive enzymes that could break down food.

The First Animals

These clusters of specialized, cooperating cells eventually became the first animals , which DNA evidence suggests evolved around 800 million years ago. Sponges were among the earliest animals. While chemical compounds from sponges are preserved in rocks as old as 700 million years, molecular evidence points to sponges developing even earlier. 

Oxygen levels in the ocean were still low compared to today, but sponges are able to tolerate conditions of low oxygen. Although, like other animals, they require oxygen to metabolize, they don’t need much because they are not very active. They feed while sitting still by extracting food particles from water that is pumped through their bodies by specialized cells.

The simple body plan of a sponge consists of layers of cells around water-filled cavities, supported by hard skeletal parts. The evolution of ever more complex and diverse body plans would eventually lead to distinct groups of animals.

The assembly instructions for an animal’s body plan are in its genes. Some genes act like orchestra conductors, controlling the expression of many other genes at specific places and times to correctly assemble the components. While they were not played out immediately, there is evidence that parts of instructions for complex bodies were present even in the earliest animals.

Thanks to their hard skeletons, sponges became the first reef builders on Earth. Scientists like Smithsonian’s Dr. Klaus Ruetzler are working to understand the evolution of the thousands of sponge species living on Earth today.  

Ediacaran Biota

By about 580 million years ago (the Ediacaran Period) there was a proliferation of other organisms, in addition to sponges. These varied seafloor creatures - with bodies shaped like fronds, ribbons, and even quilts - lived alongside sponges for 80 million years. Their fossil evidence can be found in sedimentary rocks around the world.

However, the body plans of most Ediacaran animals did not look like modern groups. Smithsonian’s Dr. Douglas Erwin , using comparative developmental evidence, has examined whether any of the fossilized Ediacaran animals were related to modern animals.

By the end of the Ediacaran, oxygen levels rose, approaching levels sufficient to sustain oxygen-based life. The early sponges may actually have helped boost oxygen by eating bacteria, removing them from the decomposition process. Tracks of an organism named Dickinsonia costata suggest that it may have been moved along the sea bottom, presumably feasting on mats of microbes.

The End-Ediacaran Extinction

However, about 541 million years ago, most of the Ediacaran creatures disappeared, signaling a major environmental change that Douglas Erwin and other scientists are still working to understand. Evolving animal body plans, feeding relationships, and environmental engineering may have played a role.

Burrows found in the fossil record, dating to the end of the Ediacaran, reveal that worm-like animals had begun to excavate the ocean bottom. These early environmental engineers disturbed and maybe aerated the sediment, disrupting conditions for other Ediacaran animals. As environmental conditions deteriorated for some animals, they improved for others, potentially catalyzing a change-over in species.

The Cambrian Explosion

The Cambrian Period (541-485 million years ago) witnessed a wild explosion of new life forms. Along with new burrowing lifestyles came hard body parts like shells and spines. Hard body parts allowed animals to more drastically engineer their environments, such as digging burrows. A shift also occurred towards more active animals, with defined heads and tails for directional movement to chase prey. Active feeding by well-armored animals like trilobites may have further disrupted the sea floor that the soft Ediacaran creatures had lived on. 

( Watch video, "The Cambrian Explosion of Life with Paleontologist Karma Nanglu." )

Unique feeding styles partitioned the environment, making room for more diversification of life. In 1909 the Smithsonian’s fourth Secretary, Charles Doolittle Walcott, discovered the Burgess Shale fossils that revealed the unprecedented biodiversity of Cambrian life. While Waptia scoured the ocean bottom, priapulid worms burrowed into the sediment, Wiwaxia attached to sponges, and Anomalocaris cruised above.

Many of these odd-looking organisms were evolutionary experiments, such as the 5-eyed Opabinia. However, some groups, such as the trilobites, thrived and dominated Earth for hundreds of millions of years but eventually went extinct. Stromatolite reef-building bacteria also declined, and reefs made by organisms called brachiopods arose as conditions on Earth continued to change. Today’s dominant reef-builders, the hard corals, did not emerge until a couple hundred million years later

However, despite all the changes that were to come, by the end of the Cambrian nearly all existing animal types, or phyla, (mollusks, arthropods, annelids, etc.) were established, and food webs were emerging, forming the foundation for the ecosystems on Earth today. 

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• 16 October 2023

How would we know whether there is life on Earth? This bold experiment found out

• Alexandra Witze

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Anything down there? Earth as seen by the Galileo probe in 1990. Credit: NASA/JPL

It began the way many discoveries do — a tickling of curiosity in the back of someone’s mind. That someone was astronomer and communicator Carl Sagan. The thing doing the tickling was the trajectory of NASA’s Galileo spacecraft, which had launched in October 1989 and was the first to orbit Jupiter. The result was a paper in Nature 30 years ago this week that changed how scientists thought about looking for life on other planets.

The opportunity stemmed from a tragic mishap. Almost four years before Galileo’s launch, in January 1986, the space shuttle Challenger had exploded shortly after lift-off, taking seven lives with it. NASA cancelled its plans to dispatch Galileo on a speedy path to Jupiter using a liquid-fuelled rocket aboard another space shuttle. Instead, the probe was released more gently from an orbiting shuttle, with mission engineers slingshotting it around Venus and Earth so it could gain the gravitational boosts that would catapult it all the way to Jupiter.

On 8 December 1990, Galileo was due to skim past Earth, just 960 kilometres above the surface. The tickling became an itch that Sagan had to scratch. He talked NASA into pointing the spacecraft’s instruments at our planet. The resulting paper was titled ‘A search for life on Earth from the Galileo spacecraft’ 1 .

The outside view

We are in a unique position of knowing that life exists on Earth. To use our own home to test whether we could discern that remotely was an extraordinary suggestion at the time, when so little was known about the environments in which life might thrive. “It’s almost like a science-fiction story wrapped up in a paper,” says David Grinspoon, senior scientist for astrobiology strategy at NASA’s headquarters in Washington DC. “Let’s imagine that we’re seeing Earth for the first time.”

It came at a time, too, when the search for life elsewhere in the Solar System was at a low ebb. US and Soviet robotic missions in the 1960s and 1970s had revealed that Venus — once thought to be a haven for exotic organisms — was hellishly hot beneath its dense clouds of carbon dioxide. Mars, crisscrossed by the ‘irrigation canals’ of astronomers’ imagination 2 , was a seemingly barren wasteland. In 1990, no one yet knew about the buried oceans that lay on Jupiter’s moon Europa — a discovery that Galileo would go on to make 3 — or on Saturn’s moon Enceladus, both of which are now seen as potential cradles of extraterrestrial life.

Crucially, Sagan and his collaborators took a deliberately agnostic approach to the detection of life, says astrobiologist Lisa Kaltenegger, who heads the Carl Sagan Institute at Cornell University in Ithaca, New York. “Of course he wants to find life, every scientist does,” she says. “But he says, let’s take that wish and be even more cautious — because we want to find it.” The existence of life was to be, in the words of the paper, the “hypothesis of last resort” for explaining what Galileo observed.

But even through this veil of scepticism, the spacecraft delivered. High-resolution images of Australia and Antarctica obtained as Galileo flew overhead did not yield signs of civilization. Still, Galileo measured oxygen and methane in Earth’s atmosphere, the latter in ratios that suggested a disequilibrium brought about by living organisms. It spotted a steep cliff in the infrared spectrum of sunlight reflecting off the planet, a distinctive ‘red edge’ that indicates the presence of vegetation. And it picked up radio transmissions coming from the surface that were moderated as if engineered. “A strong case can be made that the signals are generated by an intelligent form of life on Earth,” Sagan’s team wrote, rather cheekily.

A powerful control

Karl Ziemelis, now chief physical sciences editor at Nature , handled the paper as a rookie editor. He says it remains one of his favourites — and one of the hardest to get in. Editorial approval for the paper was far from unanimous, because it was not obviously describing something new. But, according to Ziemelis, that was mostly beside the point. “It was an incredibly powerful control experiment for something that wasn’t really on many people’s radar at the time,” he says.

“While the answer was known, it profoundly changed our way of thinking about the answer,” says Kaltenegger. Only by stepping back and regarding Earth as a planet like any other — perhaps harbouring life, perhaps not — can researchers begin to get a true perspective on our place in the Universe and the likelihood of life elsewhere, she says.

No sign of civilization in Australia. Credit: NASA/JPL

It takes on a new importance given developments since the Galileo flyby. In 1990, no planets orbiting stars other than the Sun were known. It was another two years before astronomers conclusively reported the first ‘exoplanet’ orbiting a rotating dead star known as a pulsar 4 , and three years more before they found 5 the first around a Sun-like star, 51 Pegasi. Today, scientists know of more than 5,500 exoplanets, few of which look like anything in the Solar System. They range from ‘super-Earths’ with bizarre geologies and ‘mini-Neptunes’ with gassy atmospheres to ‘hot Jupiters’, huge planets whirling close to their blazing stars.

When Sagan and his colleagues pointed Galileo at Earth, they invented a scientific framework for looking for signs of life on these other worlds — one that has permeated every search for such biosignatures since. Kaltenegger still gives Sagan’s paper to her students to show them how it is done. Life is the last, not first, inference to draw when seeing something unusual on another planet, she tells them. Extraordinary claims require extraordinary evidence.

The right mix for life

This lesson could not be more important today, as scientists stand on the verge of potentially revolutionary, and perhaps monumentally confusing, discoveries by the powerful James Webb Space Telescope (JWST). The telescope is just beginning its remote exploration of the atmospheres of dozens of exoplanets, hunting for the same sort of chemical disequilibrium that Galileo spotted in Earth’s atmosphere. It is already turning up early hints of biosignatures that might lead scientists and the public astray.

For instance, JWST has sniffed out methane in the atmosphere of at least one planet. That gas is a powerful signature of life on Earth, but it can also come from volcanoes, no life required. Oxygen captures scientists’ attention because much of it is generated by life on Earth, but it can also be formed by light splitting apart molecules of water or carbon dioxide. Finding the right combination of methane and oxygen could indicate the presence of life on another planet — but that world needs to be located in a temperate zone, not too hot nor too cold. Getting the right mix of life-sustaining ingredients in a life-friendly environment is challenging, Kaltenegger says.

The same is true for other intriguing mixes of atmospheric gases. Just last month, astronomers sifting through JWST data reported finding methane and carbon dioxide in the atmosphere of a large exoplanet called K2-18 b. They suggested that the planet might have water oceans covering its surface, and hinted at tantalizing detections of dimethyl sulfide, a compound that, on Earth, comes from phytoplankton and other living organisms 6 .

Headlines ran wild, with news stories reporting possible signs of life on K2-18 b. Never mind that the presence of dimethyl sulfide was reported with low confidence and needed further validation. Nor that no water had actually been detected on the planet. And, even if water were present, it might be in an ocean so deep as to choke off all geological activity that could maintain a temperate atmosphere.

Building evidence

Challenges such as these led Jim Green, a former chief scientist at NASA, to propose a framework in 2021 for how to report evidence for life beyond Earth 7 . A progressive scale, from one to seven, for example, could help to convey the level of evidence for life in a particular discovery, he argues. Maybe you’ve got a signal that could result from biological activity — that would just be a one on the scale. You’d need to work through many more steps, such as ruling out contamination and acquiring independent evidence of the strength of that signal before you could get to level 7 and demonstrate a true discovery of life beyond Earth.

It could take a long time. A telescope might sniff out an intriguing molecule, and scientists would argue about it. Another telescope might be built to work out the context of the observation. Each brick of evidence must be placed on top of another, each layer of mortar mixed through the arguments, scepticism and agnosticism of many, many scientists. And that’s assuming that life on another world resembles that on Earth — an assumption underlying the conclusions drawn from Galileo’s observations. “The uncertainty may last years or decades,” Grinspoon says. Sagan, who died in 1996, would have loved it.

The same year that Galileo observed Earth, Sagan convinced NASA to point another spacecraft in a direction the agency had not been planning. As Voyager 1 raced past Neptune on its way out of the Solar System, it turned its cameras back towards Earth and photographed a tiny speck, gleaming in a sunbeam. This was the iconic Pale Blue Dot image that inspired Sagan to ruminate in his 1994 book Pale Blue Dot : “That’s here. That’s home. That’s us.”

That fragile gleaming pixel reshaped how humanity visualizes its place in the Cosmos. So, too, did using Galileo to look for life on Earth, says Kaltenegger: “This is how we can use our pale blue dot to provide a template for the search for life on other planets.”

Nature 622 , 451-452 (2023)

doi: https://doi.org/10.1038/d41586-023-03230-z

Sagan, C., Thompson, W. R., Carlson, R., Gurnett, D. & Hord, C. Nature 365 , 715–721 (1993).

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Madhusudhan, N. et al. Preprint at https://arxiv.org/abs/2309.05566 (2023).

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Essays About Earth: 7 Essay Examples And Topic Ideas

There are many things you need to know about our planet, so if you’re making essays about Earth, you can read these sample essays and topic ideas.

The planet Earth is where we, humans, and other living creatures live. It also provides us with all the necessities we need – air to breathe, water to drink, and soil to grow fruits and vegetables. Without its natural resources, life would be impossible for all of us. 

Writing an essay about Earth can help give knowledge and spread awareness about climate change or look at the beauty of our planet. If you are writing an essay about the Earth, here are some essay examples and topic ideas to help you get started.

Tip: If you want to use the latest grammar software, read our guide to using an AI grammar checker .

1. Short Essay On The Structure Of Planet Earth By Shyam Soni

2. interest and concern about the fate of the earth by john olson, 3. our planet in danger by derrick wells, 4. a planet without trees: a nightmare or our future by shannon cain, 5. the possibility of an asteroid falling to earth by lewis rios, 6. save earth before colonizing mars by luz estrada, 7. my earth, my responsibility by poonam ghimire, topic idea essays about earth, 1. are there more planets like earth, 2. how has the earth’s surface changed over the years, 3. causes and effects of global warming, 4. does planting trees and reforestation help limit global warming, 5. how does population growth affect earth’s climate change, 6.  human impacts on the planet earth, 7. how did the planet earth form.

“Direct observation of the interior of the Earth is not possible as the interior becomes hotter with depth which is convincingly indicated by the volcanic eruptions. Apart from the seismological studies, other important sources of data, even though indirect, logically prove that the Earth’s body comprises several layers, which are like shells resting one above the other. These layers are distinguished by their physical and chemical properties, particularly, their thickness, depth, density, temperature, metallic content, and rocks.”

Author Shyam Soni discusses some essential facts about the structure of the planet Earth. This essay focuses on its layered structure and the differences in the density and temperature at different depths.

“I have found myself increasingly interested and concerned with the fate of the Earth and the way humankind views sustainability. In my perspective, many humans believe that Earth’s materials and resources are infinite, they will always be there to feed and maintain human life. The Earth will endlessly support and provide for the needs of the humans that inhabit it. Yet, that is just simply not true, as the human population grows we use more and more of the natural resources Earth provides.”

Author John Olson shares his point of view about the Earth’s “infinite” resources and its sustainability. However, Olson tells us that it may not be as unlimited as we think because of the rapid growth of the human population.

“Since the beginning of the Industrial Revolution in the 18th century that started in England, the people during those times were already writing down the blueprint for a problem that the succeeding generations will have to face – the increasing problem of Carbon Dioxide emissions in our atmosphere. Carbon dioxide (CO2) is released in tons, millions of tons every day in every country – released from various factories and cars most especially. This buildup of toxic gases such as the carbon dioxide heats up our planet thereby increasing the possibility, and the danger of global warming – this is what we call the greenhouse effect.”

Author Derrick Wells talks about one of the environmental problems we are facing today – the Greenhouse Effect and the actions that we could take to save our planet Earth from the danger it can pose.

“Can we imagine a world without trees? What a world without trees would look like? Could such a world even exist? Let us close our eyes, and try to imagine a desolate Earth. Imagine no more paper, and everyone would have to resort to some other source or maybe technology could help, but that is, if anyone was left at that time. Trees are an important factor to our existence not only because they produce paper, lumber, or chewing gum, but due to the fact that they serve an important role in the carbon cycle, they are the key to our very existence! Due to the ever increasing population, that seemingly distant future is getting near each passing day.”

Author Shannon Cain shares his thought about a planet without trees, telling us what it would be like and what we can do to prevent it from happening to our home planet – the Earth. 

“Jonathan Haidt gave a speech about the possibility of an asteroid falling on Earth and asked the audience what people could do to stop them. Haidt notes that if an asteroid threatens to destroy the Earth, people will forget about their differences and stand together to fight for their survival. This is what he refers a common ground in the midst of a crisis. Haidt’s video shows us the many problems that people are facing, but yet people cannot find a common ground to fight them while the issues are threatening all of us.”

Author Lewis Rios talks about the possibility of an asteroid falling on Earth and then relates it to some common problems we are facing right now. Such as poverty, which tells us that we should all cooperate and work together to find a solution to these threats to survive. 

“Has humanity irreversibly defaced Earth from being a sustainable planet for further centuries? Many would believe that humanity has come to a point of constant destruction of Earth with no hope for change. This thought process has come forth with the resolution of starting a new sustainable planet on Mars. However, it is tremendously more challenging to restart than to fix damage and change simplistic daily routines.” 

Author Luz Estrada shares her opinion about the plan of starting a new sustainable planet on Mars. Estrada shares with the readers that it is much easier to save and fix Earth – as it is now – rather than thinking of starting a new life on a different planet, which is impossible for most people.

“Earth is a beautiful living planet in the Universe and the common habitat of more than 7 billion human population and millions of species of biodiversity. Our Earth provides us with food, shelter, and most of our requirements. Despite unavoidable free services provided by the earth to humans, we are not able to pay off her kindness to us. Rather we humans are being cruel to our Earth with our selfish activities.”

Author Poonam Ghimire talks about the selfish acts that cause Earth’s slow destruction. Ghimire encourages the readers to be responsible enough to protect and preserve our planet for the next generations.

Earth, our home, is the only planet known to support life, although there are current missions determining Mars’ past and future potential for life. While scientists continue to look for signs of life elsewhere in the universe, Earth remains the only place where we’ve ever identified living creatures. If you are writing an essay about the Earth, you can use this topic idea to discuss some Earth-like planets discovered so far.

The planet Earth has not always looked the same way it looks today; the United States, a billion years ago, was in a completely different location compared to where it is today! So, how does this happen? Why does this happen? In your essay about the Earth, you can use this topic idea to give the readers some understanding of how our planet has changed over time – like the things that took place and are still taking place.

Recent global warming is mainly because of human actions, which involve releasing greenhouse gases into the atmosphere. An increase in greenhouse gases leads to a more significant greenhouse effect, which results in increased global warming. Global warming is also being felt everywhere – drought, heatwaves, melting glaciers, rising sea levels, and storms. If you are writing an essay about the Earth, you can discuss this topic in more detail to spread awareness to your readers out there.

Planting more trees is one of the most effective ways to lessen atmospheric carbon dioxide (CO2) and stop global warming. As the forests grow, they remove the carbon dioxide from the air through photosynthesis, which works as a natural reservoir to store carbon. Reforestation, one of the planned projects worldwide, is thought to help protect the environment for the next generations. You can use this topic idea for your essay about the Earth to encourage your readers to plant more trees to reduce the harmful effects of deforestation and save our home planet, Earth, from getting slowly destroyed.

Since humans require fossil fuels to power their increasingly mechanized lifestyles, human population growth is undoubtedly a significant contributor to global warming. More people mean more demand for oil, gas, coal, and other underground fuels that, when burned, release enough carbon dioxide (CO2) into the atmosphere to trap warm air inside like a greenhouse. So, in your essay about the Earth, let your readers know to what extent human population growth affects climate change and what can be done about it. 

Humans affect the planet Earth in many ways – overpopulation, pollution, burning fossil fuels, and deforestation. These things have caused global warming, soil erosion, poor air quality, and non-potable water. In your essay about the Earth, you can detail these negative impacts and how they can affect us, humans. 

The planet Earth’s formation remains a bizarre, scientific mystery. This is because we live on a planet in a solar system with seven other planets, and thousands of exoplanets have been discovered so far. However, the formation of planets like Earth is still a hotly debated topic. So, currently, there are only 2 leading theories about planetary formation – in your essay about the earth, look into this topic in more detail to share some exciting facts about the Earth with your readers. 

If you’re stuck picking your next essay topic, check out our guide on how to write a diverse essay.

If you’re still stuck, check out our general resource of essay writing topics .

Essay on Save Earth for Students and Children

500+ words essay on save earth.

Earth and the resources of earth make life possible on it. If we were to imagine our lives without these resources, that would not be possible. As life cannot function without sunshine , air, vegetation , and water . However, this is soon going to be our reality if we do not save the earth now.

The resources earth provides us with are limited. They are blessings which we do not count. Human has become selfish and is utilizing the earth’s resources at a rapid rate. We need to protect them in order to protect our lives. This is so because man and all living organisms depend on the earth for their survival.

It is The Need of the Hour

To say that saving the earth is the need of the hour would be an understatement. All the activities of humans driven by greed and selfishness have caused immense damage to the earth. It is degraded it beyond repair. Almost all the natural resources are now polluted due to these activities.

When all these resources will be under threat, naturally lives of all living organisms will be under peril. This is why we need to save the earth at all costs. All the other issues are secondary and saving the earth is the main concern. For when the earth will not remain, the other issues will go away automatically.

Earth is the only planet which can sustain life on it. We do not have a planet B which we can move onto. This makes it all the more serious to save the earth and save our lives. If we do not take strict actions now, we will lose the chance of seeing our future generations flourish forever. Everyone must come together for the same causes, as we are inhabitants of this planet firstly and then anything else.

Get the huge list of more than 500 Essay Topics and Ideas

How to Save Earth

As all human activities are impacting the lives of other organisms, humans only need to take steps to protect the earth and its resources. A little effort will go a long way on everyone’s end. Each action will make a difference. For instance, if one man decides to stop drinking bottled water, thousands of plastic can be saved from consuming.

Furthermore, we can start by planting more trees to make up for the deforestation that is happening these days at a rapid rate. When we plant more trees, ecological balance can be restored and we can improve the quality of life.

Similarly, we must stop wasting water. When done on individual levels, this will create a huge impact on conserving water. We must not pollute our water bodies by dumping waste in it. It is essential to save water most importantly as it is running out rapidly.

In short, the government and individuals must come together to save the earth. We can make people aware of the consequences of not saving the earth. They can be taught ways and how they can contribute to saving the earth. If all this collective effort starts happening, we can surely save our planet earth and make brighter earth.

{ “@context”: “https://schema.org”, “@type”: “FAQPage”, “mainEntity”: [{ “@type”: “Question”, “name”: “Why must we save the earth?”, “acceptedAnswer”: { “@type”: “Answer”, “text”: “We need to save earth right away as it is the only planet that can sustain life. Earth supports life forms which no other planet does. Moreover, all the resources are being used up rapidly so we need to save them before they all get used up.”} }, { “@type”: “Question”, “name”: “How can we save the earth?”, “acceptedAnswer”: { “@type”: “Answer”, “text”:”Everyone can take little steps to save the earth. We must not waste water and avoid the use of plastic. Moreover, we must plant more trees and encourage people to not pollute the environment.”} }] }

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Nine Reasons We’re Grateful to Live on Earth

William Steigerwald

1. we can take deep, cleansing breaths, 2. there’s solid ground to stand on, 3. the seasons go round and round, 4. its gravity doesn’t turn us into noodles, 5. we can enjoy a pleasant breeze, 6. it’s a sparkling globe of blue, white and green, 7. it’s got clear skies, sunny days and water we can swim in, 8. dry land exists and the entire world isn’t smothered beneath miles of ice, 9. cream puff clouds that come and go.

Earth can sometimes feel like the last place you’d want to be. Indeed, a number of explorers have devised inventive ways to move civilization off this planet.

It’s no surprise: The promise of a better life in the mysterious beyond can be seductive. But the fact is the more we learn about out there the more we realize how special it is here. The first astronauts to look from space back at Earth, a “pale blue dot, the only home we’ve ever known,” as scientist Carl Sagan once wrote, saw a beautiful, delicate world that is perfectly suited to the bounty of life it supports.

“When I looked up and saw the Earth coming up on this very stark, beat up lunar horizon, an Earth that was the only color that we could see, a very fragile looking Earth, a very delicate looking Earth, I was immediately almost overcome by the thought that here we came all this way to the Moon, and yet the most significant thing we’re seeing is our own home planet, the Earth,” said William Anders , a crew member on Apollo 8, the first crewed mission to the Moon.   

On this 50th anniversary of Earth Day on April 22, we reflect on nine reasons Earth is the best place to live:

Known as the Red Planet because of the rust particles in its soil that give it a reddish hue, Mars has always fascinated the human mind. What would it be like to live on this not-so-distant world, many have wondered? One day, astronauts will find out. But we know already that living there would require some major adjustments. No longer would we be able to take long, deep breaths of nitrogen- and oxygen-rich air while a gentle spring breeze grazes the skin. Without a spacesuit providing essential life support, humans would have to inhale carbon dioxide, a toxic gas we typically exhale as a waste product. On top of that, the thin Martian atmosphere (100 times thinner than Earth’s) and lack of a global magnetic field would leave us vulnerable to harmful radiation that damages cells and DNA; the low gravity (38% of Earth’s) would weaken our bones. Besides the hardships our bodies would endure, it would simply be less fun to live on Mars. Summer trips to the beach? Forget them. On Mars, there’s plenty of sand, but not a single swimming hole, much less a lake or ocean, and the average temperature is around minus 81 degrees Fahrenheit (minus 63 degrees Celsius). Even the hardiest humans would find the Martian climate to be a drag. —Staci Tiedeken, planetary science outreach coordinator, NASA’s Goddard Space Flight Center

Earth has grassy fields, rugged mountains and icy glaciers. But to live on the Sun, we’d have to kiss all solid ground goodbye. The Sun is a giant ball of plasma, or super-heated gas. If you tried to stand on the Sun’s visible surface, called the photosphere, you’d fall right through, about 205,000 miles (330,000 kilometers) until you reached a layer of plasma so compressed, it’s as thick as water. But you wouldn’t float, because you’d be crushed by the pressure there: 4.5 million times stronger than the deepest point in the ocean. Get ready for a quick descent, too. The Sun’s gravity is 28 times stronger than Earth’s. Thus, a 170-pound (77-kilogram) adult on Earth would weigh an extra 4,590 pounds (2,245 kilograms) at the Sun. That would feel like wearing an SUV on your back! If a person managed to hover in the photosphere, though, it might get a little warm. The temperature there is around 10,000 degrees Fahrenheit (5,500 Celsius), about five to 10 times hotter than lava — yet, not nearly the hottest temperature on the Sun. Don’t worry, though, there would be a break of 3,000 degrees Fahrenheit (1,600 degrees Celsius) if you stumbled on a sunspot, which is a “cool” region formed by intense magnetic fields. These conditions would have even the most intrepid adventurers longing for the comforts of home. —Miles Hatfield, science writer, NASA’s Goddard Space Flight Center

Since the beginning of recorded history, people have tracked and celebrated nature’s transition from the desolate days of winter, to the brilliant radiance of spring, to the endless days of summer, and so on. Seasons come from a planet’s tilt on its axis (Earth’s is 23.5 degrees), which tips each hemisphere either toward or away from the heat of the Sun throughout the year. Venus , barely tilted on its axis, has no seasons, though there are hints that it may have once looked and behaved much like Earth , including having oceans covering its rocky surface. But these days, our neighboring planet has an atmosphere so thick (55 times denser than Earth’s) it helps keep Venus at a searing 900 degrees Fahrenheit (465 degrees Celsius) year round — that’s hotter than the hottest home oven. This oppressive atmosphere also blots out the sky, making it impossible to stargaze from the surface. But Venus isn’t all bad. Despite the low quality of life, there is one benefit of living there: The Venusian year (225 Earth days) is shorter than its day (243 Earth days). That means you can celebrate your birthday every day on Venus! —Lonnie Shekhtman, science writer, NASA’s Goddard Space Flight Center

Capturing the imaginations of scientists and sci-fi writers alike, black holes are extremely compact objects that do not let any light escape. The surface of a black hole is an area called the “event horizon,” a boundary beyond which nothing can ever return. Even if we were fortunate enough to have a spaceship that could travel to a relatively nearby black hole, its gravity is so strong that approaching too close would stretch and compress the spacecraft and everyone inside it into a noodle shape — a fate scientists call “spaghettification.” Making matters even weirder, time ticks by more slowly around a black hole. To someone watching from far away as a spaceship fell into the event horizon, the vehicle would appear to slow down more the closer it got — and never quite get there. Fortunately, there are no known black holes in the vicinity of Earth or anywhere in the solar system, so we’re safe for now. And we’re lucky that Earth has just the right amount of gravity — enough so we don’t go flying away, but not so much that we can’t stand up and run around. If you still think traveling to a black hole would be a good idea, check out this black hole safety video . —Elizabeth Landau, writer, NASA Headquarters

Jupiter’s breathtaking swirls of colorful cloud bands might make this planet an appealing vacation destination … for skydivers. They’d need to bring along their own oxygen, since Jupiter’s atmosphere is made mostly of hydrogen and helium (same as our Sun), with clouds of mostly ammonia. Descending through Jupiter ’s clouds is for the most extreme thrill seekers. Given the planet’s strong gravity and super-fast rotation on its axis compared to Earth (10 hours vs. 24 hours), a skydiver would tumble 2.5 times faster than they would on Earth, while getting knocked around by winds raging between 270 and 425 miles per hour (430 to 680 kilometers per hour). Jupiter’s winds make Earth’s highest category hurricane feel like a breeze, and its lightning strikes are up to 1,000 times more powerful than ours. Even if a skydiver does make it through the hundreds of miles, or kilometers, of atmosphere, plus crushing air pressure and extreme heat, it’s not clear they’ll reach a solid surface. Scientist don’t know yet whether Jupiter, a giant planet that can fit 1,300 Earths inside of it, has a solid core. Having solid ground to stand is starting to sound like a luxury. —Staci Tiedeken, planetary science outreach coordinator, NASA’s Goddard Space Flight Center

In places where ocean tides are highest on Earth, the difference between low and high tide is about 50 feet (15 meters). Compare that to Io. This moon of Jupiter is caught in a tug-of-war between the planet’s massive gravity and the pulling of two neighboring moons, Europa and Ganymede. These forces cause Io’s surface to regularly bulge up and down by as much as 330 feet (100 meters) — and we’re talking about rock, not water. All this motion has consequences: Io’s interior is very hot, making this moon the most volcanically active world in the solar system. Io , which from space looks like a moldy cheese pizza, has hundreds of volcanoes. Some erupt lava fountains dozens of miles (or kilometers) high. Between all the lava, a thin sulfur dioxide atmosphere and intense radiation from nearby Jupiter, Io doesn’t offer much of a beach vacation for humans. —Bill Dunford, writer and web producer, NASA’s Jet Propulsion Laboratory

If there is one place in the universe we know of that could compete with Earth as a home for humans, Titan is it. This satellite of Saturn is the second largest moon in our solar system after Ganymede. Titan is in some ways the most similar world to ours that we have found. Its thick atmosphere would remind us of home, though the air pressure there is slightly higher than Earth’s. The atmosphere would defend humans against harmful radiation. Like Earth, Titan also has clouds, rain, lakes and rivers, and even a subsurface ocean of salty water. Even the moon’s terrain and landscape look eerily similar to some parts of Earth. While Titan sounds promising, it has major flaws. Chief among them is oxygen — there isn’t any in the atmosphere. And those lovely rivers and lakes? They’re made of liquid methane. So don’t pack your bathing suit just yet; our bodies are denser than the methane, so they’d sink like boulders. Another thing you’d miss on Titan is seeing the Sun above your head, dazzling against an azure sky. Not only is Titan much farther from the Sun than is Earth, its hazy atmosphere dims the sunlight, making daytime appear like twilight on Earth. —Lonnie Shekhtman, science writer, NASA’s Goddard Space Flight Center

Jupiter’s moon Europa is one of the best places to search for life beyond Earth. It may harbor more liquid water than all of Earth’s oceans combined. Just picture yourself standing on a warm, sandy beach, admiring the sunlight glimmering on an ocean that reaches from horizon to horizon. And then prepare to be disappointed. Europa’s ocean is global. It has no beach. No shore. Only ocean, all the way around. Sunlight doesn’t glimmer on the water and there are no waves because Europa’s ocean is hidden beneath miles — perhaps tens of miles — of ice that encases the entire moon. Europa is also tidally locked, meaning if a person stood on its Jupiter-facing side (like our Moon, one hemisphere always faces its parent planet), the solar system’s largest planet would loom overhead and never set. A sublime setting for a romantic stroll? No. Europa has a practically nonexistent atmosphere and brutally cold temperatures ranging from about minus 210 to minus 370 degrees Fahrenheit (minus 134 to minus 223 degrees Celsius). A spacesuit might help with the temperature and pressure, but it can’t protect against those pesky atomic particles captured in Jupiter’s magnetic field, endlessly lashing Europa with such energy that they can blast apart molecules and ionize atoms. Europa’s ionizing radiation would damage or destroy cells in the human body, leading to radiation sickness. —Jay R. Thompson, writer, NASA’s Jet Propulsion Laboratory

With more than 4,000 planets discovered so far outside our solar system, called “ exoplanets ,” we don’t know of any that offers the comforts of Earthly living — and many would be downright nightmares. Take Kepler-7b , for example, a gas giant with roughly the same density as foam board. That means it could actually float in a bathtub (fun fact: so could Saturn). Like other exoplanets called “hot Jupiters,” this one is really close to its star — a “year,” one orbit, takes just five Earth days. One side always faces the star, just like one side of the Moon always faces Earth. That means it’s always hot and light on one half of this planet; on the other, night never ends. If you’re bummed out by cloudy days on Earth, consider that one side of Kepler-7b always has thick, unmoving clouds, and those clouds may even be made of evaporated rock and iron. And at more than 2,400 degrees Fahrenheit (1,316 degrees Celsius), Kepler-7b would be a real roaster to visit, especially on the dayside. It’s amazing to learn about how different exoplanets can be from Earth, but we’re glad we don’t live on Kepler-7b. —Kristen Walbolt, digital and social media producer/strategist, NASA’s Jet Propulsion Laboratory

More information here .

Last Updated: Apr 22, 2020

Editor: Svetlana Shekhtman

Home — Essay Samples — Science — Earth Science — The Beauty of Earth: An Essay on the Magnificence of Our Planet

The Beauty of Earth: an Essay on The Magnificence of Our Planet

• Categories: Earth Science

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Published: Mar 8, 2024

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The natural wonders of earth, the diverse inhabitants of earth, preserving the beauty of earth.

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Opinion Guest Essay

The Soul of Soil

Credit... Sarah Meadows

Supported by

By Ferris Jabr

Mr. Jabr is the author of “ Becoming Earth: How Our Planet Came to Life .”

• Aug. 4, 2024

When my partner and I bought our home in Portland, Ore. four years ago, we immediately began designing our dream garden, intending to replace a derelict grass lawn with ample beds of lush, long-blooming perennials. We soon discovered, however, that our soil was unyielding, clay-heavy and strewed with rubble. In previous, much tinier gardens, I’d circumvented such difficulties with a few bags of high-quality soil from the nursery. Replacing this vastly greater quantity of dirt was neither practical nor financially feasible. Instead, I resolved to remediate what we already had.

Learning how to do so transformed much more than our yard — it completely changed the way I think about soil, and about our planet as a whole. I now see soil not simply as a medium for life, but as a living entity in its own right — one that is rapidly going extinct.

In some parts of the world, intensive farming, overgrazing and deforestation are destroying soil up to 1,000 times as fast as the base line rate of erosion. If current trends continue, 90 percent of the planet’s habitable land areas could be substantially degraded by 2050, causing crop yields to drop by an average of 10 percent — and up to 50 percent in some areas — and most likely forcing up to hundreds of millions of people to migrate.

The eradication of soil could culminate in the collapse of complex terrestrial life — unless we rethink our relationship to the world beneath our feet.

Soil is the result of eons of planetary evolution — billions of years of the elements weathering rock and more than 425 million years of interactions with complex life. A single inch of fertile topsoil requires centuries to develop.

Microbes, fungi, plants and animals create and maintain soil through myriad processes: by breaking apart rock with roots and secreted acids; enriching fragmented rock with their own remains and byproducts; and circulating air, water and nutrients via crawling, slithering and burrowing.

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An Informative Essay on Life on Earth In 150 Words

The planet Earth is the only home that we have. Many people have different opinions on what makes life worth living, but with so much to talk about, it can be hard to separate truth from fiction. What do you think makes life worth living?

Table of Contents

Importance Life On Earth Essay For Students

What is life on earth.

Life on earth is a complex and fascinating phenomenon. It began with simple organic molecules and evolved through the ages to include animals, plants, and fungi. Scientists are still trying to understand all the details of life on earth, from its origins to its future. In this essay, we’ll explore some of the most important questions about life on earth.

An Overview of Life on Earth

Life on Earth is a beautiful and amazing phenomenon. From the first moment of existence, organisms have been striving to survive, grow, and thrive. This endless cycle of growth and development has led to the magnificent life we see today on our planet.

The diversity of life on Earth is simply astounding. From single-celled organisms to towering trees, every form of life has its own special way of surviving and thriving. No matter how different they may seem at first glance, all organisms share one common attribute – they are capable of reproducing themselves.

This ability to reproduce is what allows life to continue evolving and adapting over time. The ever-changing environment provides new opportunities for organisms to thrive, and as a result, they evolve into new and unique forms.

In short, life on Earth is a miraculous phenomenon that is constantly evolving and changing in interesting and unexpected ways. Thanks for reading!

How does life function on Earth?

The answer to this question is far from simple, and it has been debated by scientists and philosophers for centuries. However, the most general consensus in the scientific community is that life on Earth functions by harnessing energy from the sun. This energy is converted into chemical energy, which is then used to create biomolecules such as proteins and DNA. These biomolecules then interact with each other to create complex systems, including plants, animals, and humans.

Problems and risks: what are the dangers to life on Earth?

Life on Earth is in danger from a number of sources. The dangers to life on Earth come from a variety of sources, including natural disasters, environmental degradation, and human actions. Each year, a large number of people die as a result of these dangers.

Natural Disasters: Natural disasters cause death and injury to people all over the world. Natural disasters can be caused by weather conditions such as hurricanes, floods, earthquakes, or tornadoes. They can also be caused by animals, such as pandemics or animal attacks. Natural disasters can also be caused by human activities, such as mining accidents or nuclear accidents.

Environmental Degradation: Environmental degradation results in the loss of natural resources and the destruction of habitats. This can cause wildlife to become extinct, decrease food supplies, and increase pollution levels. Environmental degradation can also lead to the release of harmful chemicals into the environment.

Human Actions: Human actions can also endanger life on Earth. Human activities that endanger life on Earth include the use of pesticides, the disposal of waste products, and the use of fossil fuels. Human actions that protect life on Earth include the promotion of renewable energy sources and the conservation of natural resources.

In conclusion, life on earth is a fascinating and complex journey. We are constantly evolving as a species, and our planet is in the midst of some very big changes. As we learn more about our planet and its systems, it’s evident that we need to take care of it – for our own sake, and for the sake of future generations. Thank you for reading this essay on life on earth – I hope you have enjoyed learning about all of the incredible things happening here on Earth.

Hello! Welcome to my Blog StudyParagraphs.co. My name is Angelina. I am a college professor. I love reading writing for kids students. This blog is full with valuable knowledge for all class students. Thank you for reading my articles.

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Short Essay on Our Planet Earth [100, 200, 400 words] With PDF

Earth is the only planet that sustains life and ecosystems. In this lesson, you will learn to write essays in three different sets on the planet earth to help you in preparing for your upcoming examinations.

Short Essay on Our Planet Earth in 100 Words

Earth is a rare planet since it is the only one that can support life. On Earth, life is possible for various reasons, the most essential of which are the availability of water and the presence of oxygen. Earth is a member of the Solar System. The Earth, along with the other seven planets, orbits the Sun.

One spin takes approximately twenty-four hours, and one revolution takes 365 days and four hours. Day and night, as well as the changing of seasons, occurs due to rotation and revolution. However, we have jeopardized our planet by our sheer ignorance and negligence. We must practise conservation of resources and look after mother earth while we have time.

Short Essay on Our Planet Earth in 200 Words

Earth is a blue planet that is special from the rest of the planets because it is the only one to sustain life. The availability of water and oxygen are two of the most crucial factors that make life possible on Earth. The Earth rotates around the Sun, along with seven other planets in the solar system. It takes 24 hours to complete one rotation, and approximately 365 days and 4 hours to complete one revolution. Day and night, as well as changing seasons, are all conceivable due to these two movements. 

However, we are wasting and taking advantage of the natural resources that have been bestowed upon us. Overuse and exploitation of all-natural resources produce pollution to such an alarming degree that life on Earth is on the verge of extinction. The depletion of the ozone layer has resulted in global warming. The melting of glaciers has resulted in rising temperatures.

Many animals have become extinct or are endangered. To protect the environment, we must work together. Conversation, resource reduction, reuse, and recycling will take us a long way toward restoring the natural ecosystem. We are as unique as our home planet. We have superior intelligence, which we must employ for the benefit of all living beings. The Earth is our natural home, and we must create a place that is as good as, if not better than, paradise.

Short Essay on Our Planet Earth in 400 Words

Earth is a unique planet as it is the only planet that sustains life. Life is possible on Earth because of many reasons, and the most important among them is the availability of water and oxygen. Earth is a part of the family of the Sun. It belongs to the Solar System.

Earth, along with seven other planets, revolves around the Sun. It takes roughly twenty-four hours to complete one rotation and 365 days and 4 hours to complete one revolution. Rotation and revolution make day and night and change of seasons simultaneously possible. The five seasons we experience in one revolution are Spring, Summer, Monsoon, Autumn, and Winter.

However, we are misusing resources and exploiting the natural gifts that have been so heavily endowed upon us. Overuse and misuse of all the natural resources are causing pollution to such an extent that it has become alarming to the point of destruction. The most common form of pollution caused upon the earth by us is Air Pollution, Land Pollution, Water Pollution, and Noise Pollution.

This, in turn, had resulted in Ozone Layer Depletion and Global Warming. Due to ozone layer depletion, there harmful ultraviolet rays of the sun are reaching the earth. It, in turn, is melting glaciers and causing a rise in temperature every year. Many animals have either extinct or are endangered due to human activities.

Some extinct animals worldwide are Sabre-toothed Cat, Woolly Mammoth, Dodo, Great Auk, Stellers Sea Cow, Tasmanian Tiger, Passenger Pigeon, Pyrenean Ibex. The extinct animals in the Indian subcontinent are the Indian Cheetah, pink-headed duck, northern Sumatran rhinoceros, and Sunderban dwarf rhinoceros.

The endangered animals that are in need of our immediate attention in India are Royal Bengal Tiger, Snow leopard, Red panda, Indian rhinoceros, Nilgiri tahr, Asiatic lion, Ganges river dolphin, Gharial and Hangul, among others. We have exploited fossil fuels to such an extent that now we run the risk of using them completely. We must switch to alternative sources of energy that are nature friendly. Solar power, windmills, hydra power should be used more often, and deforestation must be made illegal worldwide.

We must come together to preserve the natural environment. Conversation, reduction, reuse and recycling of the resources will take us a long way in rebuilding the natural habitat. We are as unique as our planet earth. We have higher intelligence, and we must use it for the well-being of all living organisms. The Earth is our natural abode, and we must make a place as close to Paradise, if not better.

Hopefully, after going through this lesson, you have a holistic idea about our planet Earth. I have tried to cover every aspect that makes it unique and the reasons to practise conversation of natural resources. If you still have any doubts regarding this session, kindly let me know through the comment section below. To read more such essays on many important topics, keep browsing our website. 

Join us on Telegram to get the latest updates on our upcoming sessions. Thank you, see you again soon.

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July 29, 2024

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Complex life on Earth began around 1.5 billion years earlier than previously thought, new study claims

by Cardiff University

Environmental evidence of the very first experiments in the evolution of complex life on Earth, has been uncovered by an international team of scientists.

Until now, scientists broadly accepted animals first emerged on Earth 635 million years ago.

But a team, led by Cardiff University, has discovered evidence of a much earlier ecosystem in the Franceville Basin near Gabon on the Atlantic coast of Central Africa over 1.5 billion years earlier.

Their study, presented in Precambrian Research , describes an episode of unique underwater volcanic activity following the collision of two continents, which created a nutrient-rich 'laboratory' for the earliest experiments in complex biological evolution. The paper is titled "Hydrothermal seawater eutrophication triggered local macrobiological experimentation in the 2100 Ma Paleoproterozoic Francevillian sub-basin."

Dr. Ernest Chi Fru, the paper's lead author and Reader at Cardiff University's School of Earth and Environmental Sciences, said, "The availability of phosphorus in the environment is thought to be a key component in the evolution of life on Earth, especially in the transition from simple single cell organisms to complex organisms like animals and plants.

"We already know that increases in marine phosphorus and seawater oxygen concentrations are linked to an episode of biological evolution around 635 million years ago. Our study adds another, much earlier episode into the record, 2.1 billion years ago."

Scientists have widely debated the validity of large-sized fossils of macroorganisms from this period, which are the earliest of their kind in the geologic record.

But the Cardiff-led team identified a link between environmental change and nutrient enrichment prior to their emergence which might have triggered their evolution.

The team's geochemical analysis of the marine sedimentary rocks deposited 2.1 billion years ago sheds new light on this much-disputed body of unusually large-sized fossils in the Francevillian basin.

Dr. Chi Fru added, "We think that the underwater volcanoes, which followed the collision and suturing of the Congo and São Francisco cratons into one main body, further restricted and even cut off this section of water from the global ocean to create a nutrient-rich shallow marine inland sea.

"This created a localized environment where cyanobacterial photosynthesis was abundant for an extended period of time, leading to the oxygenation of local seawater and the generation of a large food resource.

"This would have provided sufficient energy to promote an increase in body size and greater complex behavior observed in primitive simple animal-like life forms such as those found in the fossils from this period."

However, the restricted nature of this water mass, together with the hostile conditions that existed beyond the bounds of this environment for billions of years later, likely prevented these enigmatic life forms from taking a global foothold, the researchers say.

Their study suggests that these observations may point to a two-step evolution of complex life on Earth.

Step one followed the first major rise in atmospheric oxygen content 2.1 billion years ago and step two followed a second rise in atmospheric oxygen levels some 1.5 billion years later.

"While the first attempt failed to spread, the second went on to create the animal biodiversity we see on Earth today," he says.

The team is working on putting better constraints on the environmental conditions that explain the appearance of these enigmatic fossils.

Provided by Cardiff University

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Essay On Earth – 10 Lines, Short And Long Essay For Kids

• Key Points To Remember When Writing An Essay On Earth For Lower Primary Classes
• 5 Lines On The Earth For Children
• 10 Lines On The Earth For Kids
• A Paragraph On Earth For Children
• Short Essay On Earth In English For Kids
• Long Essay On Earth In English For Children

Amazing Facts About Earth For Kids

• What Will Your Child Learn From The Essay On Earth?

The Earth plays a vital role in our lives. It provides us with habitat, water, food, etc. The Earth came into existence millions of years ago, and there have been billions of animals and humans that have walked the same Earth as we do now. The Earth is home to over 5 million species of plants and animals, most of which have still not been identified or recorded. Essay on Earth in English is a common subject in schools as it is an important topic for children to think about and discuss. The Earth can be studied and written about in many different ways; you can write about it in terms of climate change, species, land formation, water composition and even the formation of the solar system and Earth’s position in it. The possibilities are endless! Here, we will discuss essay on Earth for class 1, 2 & 3 for kids.

Key Points To Remember When Writing An Essay On Earth For Lower Primary Classes 

Essay writing is an important skill that children must excel at as it helps them in life. Making their foundations strong helps to develop their skills and focus on improving the content of their essays. While writing essays, there are a few key points that one must remember –

• The language must be simple and comprehensible. 
• Teach words and sentences that your child understands and will be able to write when not assisted. 
• Focus on the very basics, as this is for a lower primary class; children aren’t expected to write in detail.  
• A good place to start would be what the Earth means to us as humans. What the Earth provides us with.  
• Take care of the format of the essay. If in paragraph form, ensure that each paragraph is neither too short nor too long. 
• Be clear about the direction of the essay in the beginning to ensure consistency. 
• Keeping track of the word limit is key. 

5 Lines On The Earth For Children 

For young children, we will stick to the very basics in this form of the essay. We will note down five basic points about the Earth we live on. We will progressively increase the intensity.  

• The Earth orbits the Sun, which is the centre of our Solar System. 
• Earth is the 3rd planet in our Solar System out of eight in total. 
• It is the only planet which supports life. 
• It has both land and water bodies. 
• It has rivers, valleys, mountains, hills, forests, oceans, plains and beaches.  

10 Lines On The Earth For Kids 

Now that we have some basics laid down, we can start adding more details. If we closely observe the essay lines above, we can see the flow of information. We start off with the position of the Earth in the Solar System and then come down to the geographical features of the Earth. Now, we can go into more detail for an essay for class 1 and 2.

Here’s how to describe Earth in a few lines –

• Our Earth is located in the Milky Way galaxy. 
• The Sun is the centre of the Solar System, with eight planets revolving around it. 
• Earth is the 3rd planet from the Sun, and it has one Moon. 
• It is the only planet in our Solar System which is suitable for sustaining life. 
• The composition of the Earth’s surface is 70% water and only 30% land. 
• Water bodies such as oceans, rivers, lakes, glaciers and seas make up 70% of the water content on Earth. 
• Landforms such as mountains, hills, plateaus and plains are the four major types of land we see on Earth. 
• The water bodies are home to aquatic animals such as fishes of different species and mammals, crustaceans, reptiles and more.
• Landforms are home to plants, vertebrates, and invertebrates such as lizards, elephants, eagles, sunflowers, and of course, us humans! 
• The Earth provides land and aquatic animals with food, water and shelter. We would not have existed without the Earth! 

A Paragraph On Earth For Children 

Now that we are comfortable with writing essays (information) in a numeric form, we can move along to writing essays in paragraph form. Below is a short paragraph on Earth.

Millions of years ago, the Earth was formed in one small corner of the galaxy named the Milky Way. The Big Bang caused the formation of the Sun, eight planets, their moons, and other bodies, such as dwarf planets (Pluto!). The Earth is the only planet in our Solar System which could sustain life. This is due to its strategic position; it is not too close to the Sun, nor is it too far away from the Sun. This, coupled with the right elements, allowed landforms and water bodies to form. This, in turn, supported the evolution of life on Earth. Indeed, the Earth is one of a kind! 

Short Essay On Earth In English For Kids 

Moving on to a slightly longer form of essay, we can start adding in more information and maybe even add paragraphs. Since you have limited words, be choosy about what you wish to write and what you wish to omit. Below is an essay for class 1, 2 and 3 on Earth.

The Milky Way galaxy is home to many stars, planets and planetary systems. One such planetary system is our Solar System. Our Solar System has eight planets, of which Earth is the fourth. The Earth rotates on its axis, which causes days and nights. It also revolves around the Sun in a fixed orbit, which causes the change in seasons.

The strategic position and movement of the Earth support the millions of species of plants and animals that inhabit it. The right elements and external forces allowed the formation of land and water bodies which provide homes and nutrients to the millions of species on the planet.

Water bodies such as oceans, rivers and lakes are homes to aquatic animals like fishes, whales and sea horses. Landforms are home to plants, animals and insects. However, in more recent times, we humans have been overusing our resources as well as polluting the environment, which is negatively affecting the planet and our co-habitants. We must strive to save the planet now before it is too late. 

Long Essay On Earth In English For Children 

Lastly, we will discuss and look at long-form essay for class 3. Since we have more words to play with, we can start going in-depth and look at specific topics. We can also add sub-heads and paragraph breaks. We will first start with an introduction, followed by the subheads.

The Earth is unique. It is indeed one of a kind. When the Big Bang occurred, the right elements, temperature and pressure (among other factors) created the Earth. Subsequently, the topography and the organisms emerged. Years of evolution have brought us to today, where we can study and understand not only the Earth but also other planets and galaxies.  

What Is Earth? 

The word ‘Earth’ is a Germanic word which simply means “the ground.” Earth is the only planet known that homes and nurtures living organisms such as ourselves. It is the fifth largest planet in our Solar System. It is also the only planet which has water on its surface. About 71% of the Earth’s surface is water, while the remaining 29% is land. It has one natural satellite, the Moon. 

Origin Of The Planet Earth 

The beginning of our Universe was the Big Bang. It was too hot, but it slowly cooled down. Different particles started bumping into each other, eventually forming common elements. Our solar system was formed roughly 8.7 years after the Big Bang. All solar systems begin in the same way – from Nebulas. Collapsing of dust and gas molecules within the nebulae causes the formation of planets and stars. The gravitational pull comes into action here and pulls the gas molecules and dust particles together. As these particles increase in size, the attraction between the molecules increases. This eventually forms a planet. However, the planet was still too hot to sustain life. Eventually, the planet began cooling down. The oceans are where the origin of life occurred. Slowly, evolution caused organisms to move onto land too. Over millions of years, the Earth has gone through many cycles of heating up and cooling down. This has resulted in mass extinctions and the wipeout of civilizations and organisms. However, planet Earth has managed to give birth to new organisms and help them evolve every single time. 

Different Layers Of The Earth 

The Earth is made up of three layers – The Crust, The Mantle and The Core 

1. The Crust  

This is the outer-most part of the Earth. It is mostly made up of solid rock and minerals. It is about 40km in thickness and is only 1% of the Earth’s mass. However, this part of the Earth harbours all known life in the Universe.  

2. The Mantle 

This is the middle part of the Earth. It is about 2900kms in thickness, and it consists of hot, dense, iron and magnesium-rich solid rock. The Crust and the Mantle make up the lithosphere, which is broken into plates, both large and small.  

3. The Core 

The core is the innermost part of the Earth. It is further divided into two parts – the liquid outer core and the solid inner core. The temperatures here can rise upwards of 50,000 C.  

Motion Of The Earth 

The Earth has mainly two motions – Rotation and Revolution.  

1. Rotation

The Earth rotates on its axis in a clockwise motion. It takes the Earth 23.9 hours to complete one rotation on its axis. The rotation of the Earth causes the change in day and night. 

2. Revolution

The Earth revolves around the Sun in a fixed orbit in an anticlockwise direction. It takes the Earth 365 days, 6 hours, and 9 minutes to complete one rotation around the Sun. The revolution of the Earth causes the change in seasons.  

How Can We Protect The Mother Earth? 

There are many ways we can protect our Earth. Some ways are: 

• Be conscious about overusing and overexploiting resources. 
• Conserve energy, both fuel and electricity. 
• Do not pollute your surroundings, especially with plastic. 
• Remember the 3Rs – Reuse, Recycle and Reduce. 
• Strive to conserve your local flora and fauna.  

Below are something amazing facts about our Earth for kids:

• The name ‘Earth’ comes from the old English and Germanic words that mean ‘the ground’.  
• The Earth orbits around the sun at a whopping speed of 30 kilometres per second!  
• The Earth’s diameter is 12,800 kilometres, making it the 5 th largest planet in our solar system.  
• The Earth is the only planet known to support life. The availability of abundant oxygen and water makes this possible.  
• Due to the Moon slowing down Earth’s rotation, the days on Earth are, in fact, getting longer!  

What Will Your Child Learn From The Essay On Earth? 

Your child will learn a lot about our planet, its origins, its movements, etc. The essay on planet earth will also help your child learn how to write a good composition with perfect techniques. This article takes you through essay writing in a step-by-step manner.

1. Why Planet Earth Is Called A Blue Planet? 

Planet Earth is called the Blue Planet because 71% of its surface is covered with water. 

2. When Is World Earth Day Celebrated? 

World Earth Day is celebrated on 22nd April every year.  

Essay On The Sun for Kids Save The Earth Essay for Lower Primary Class Children 10 Lines, Short and Long Essay on Environment for Kids

• Essays for Class 1
• Essays for Class 2
• Essays for Class 3

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Essay on Earth And Life Science

Students are often asked to write an essay on Earth And Life Science in their schools and colleges. And if you’re also looking for the same, we have created 100-word, 250-word, and 500-word essays on the topic.

Let’s take a look…

100 Words Essay on Earth And Life Science

What is earth and life science.

Earth and Life Science is a fascinating subject that explores our world and the life within it. It is a blend of two sciences: Earth Science and Life Science. Earth Science studies the Earth’s physical aspects like rocks, oceans, and atmosphere. Life Science, on the other hand, focuses on living organisms, their structure, function, and evolution.

Why Study Earth and Life Science?

Studying Earth and Life Science helps us understand our planet and the life it supports. This knowledge is vital for many reasons. It helps us predict natural disasters, understand climate change, and conserve biodiversity. It also guides us in making informed decisions about resources.

Branches of Earth and Life Science

Earth and Life Science is divided into many branches. In Earth Science, we have geology (study of rocks), meteorology (study of weather), and oceanography (study of oceans). In Life Science, we have biology (study of life), botany (study of plants), and zoology (study of animals).

Role of Earth and Life Science in Daily Life

Earth and Life Science plays a crucial role in our daily life. It helps us predict weather for planning outdoor activities. It aids farmers in understanding soil and climate for better crop production. Moreover, it helps doctors and scientists understand diseases and develop new medicines.

Future of Earth and Life Science

250 words essay on earth and life science, understanding earth and life science.

Earth and Life Science is a field of study that explores the natural world around us. It focuses on understanding the Earth, its structure, and how life forms interact with their environment.

The Earth’s Structure

The Earth is made up of several layers. The crust is the outermost layer that we live on. Beneath it is the mantle, a hot, flowing layer of rock. The core, at the center of the Earth, is divided into two parts: the outer core, which is liquid, and the inner core, which is solid.

Life Science

Life Science is about understanding living things. It studies how plants, animals, and humans function and interact with the environment. It also explores how life evolved over time, leading to the diversity we see today.

The Connection Between Earth and Life Science

The connection between Earth and Life Science is crucial. The Earth provides the environment for life to exist. The nature of the environment, such as the climate and available resources, influences the type of life that can survive there.

Importance of Earth and Life Science

Studying Earth and Life Science helps us understand our world better. It teaches us about natural events like earthquakes and hurricanes, and about the diversity of life on our planet. This knowledge can help us make informed decisions to protect our planet and its inhabitants.

500 Words Essay on Earth And Life Science

Earth and Life Science is a fascinating field of study that helps us understand our world and the life forms that live in it. It is a combination of two major sciences. Earth Science studies the Earth, its structure, and how it changes over time. Life Science, on the other hand, focuses on living things, their functions, and their interactions with the environment.

Understanding Earth Science

Earth Science is like a detective story about our planet. It looks at the Earth’s layers, from the deepest core to the outer atmosphere. It investigates how mountains form, why earthquakes happen, and what causes volcanoes to erupt. Scientists in this field also study the weather and climate patterns to predict future conditions.

Exploring Life Science

How are earth and life science connected.

Earth and Life Science are closely connected. The Earth provides the environment where life exists. For example, the water cycle studied in Earth Science is essential for all life forms. Likewise, the atmosphere that Earth Science studies protects us from harmful solar radiation and helps maintain the right conditions for life.

In return, living things also affect the Earth. For instance, plants help create oxygen and reduce carbon dioxide in the atmosphere, which impacts the Earth’s climate.

Why is Earth and Life Science Important?

Earth and life science in everyday life.

Even if we don’t realize it, Earth and Life Science are part of our everyday life. When we check the weather forecast, we are using data from Earth Science. When we take medicine to fight off an illness, we are applying knowledge from Life Science.

In conclusion, Earth and Life Science are fascinating fields that help us understand our world and the life it supports. They are also incredibly important, influencing many aspects of our daily lives and helping us make informed decisions about our future.

That’s it! I hope the essay helped you.

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Was life on Earth sparked by cloud-to-ground lightning strikes?

Harvard researchers demonstrate how cloud-to-ground lightning strikes could have created the building blocks for life in the young Earth.

One of the most fundamental questions in science is how life began on Earth. 

Now, scientists may be a step closer to answering that query, finding that lightning on primordial Earth may have been the spark that lit the fuse of life on our planet.

One of the major questions regarding the beginning of life on Earth revolves around how the building blocks for life , such as nitrogen and carbon, emerged on our young planet. The three leading theories include delivery by asteroids and comets that crashed into Earth, emissions from deep-sea vents, and cloud-to-ground lightning strikes. 

According to a team of chemists from Harvard University, that last option is looking mighty likely. 

Related: The building blocks of life can form rapidly around young stars

"Cloud-to-ground lightning strikes could have generated high concentrations of reactive molecules locally, establishing diverse feedstocks for early life to emerge and survive globally," wrote the team in paper a published in the journal Proceedings of the National Academy of Sciences (PNAS)

 This is far from the first experiment to suggest cloud-to-ground lightning as a potential key to unlocking life on Earth. American chemist and Nobel Prize winner Harold Urey and his research student Stanley Miller performed a similar experiment, appropriately dubbed the Urey-Miller experiment, in 1953. 

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They ran an electrical arc as a proxy for lightning through a combination of methane, ammonia, hydrogen, and water — what they thought was the composition of the young Earth's atmosphere — and produced amino acids, which are necessary for the creation of life. 

While the science still holds, we now suspect the young atmosphere is comprised of carbon dioxide and nitrogen. Thus, the Harvard team performed an updated version of the Urey-Miller experiment.

In their lab, the researchers simulated cloud-to-ground lightning strikes in a biosphere that mimicked conditions on a young Earth. They studied the chemical reactions from the strikes, discovering "remarkable yields" of carbon dioxide being reduced into carbon monoxide and formic acid and nitrogen being converted into nitrate, nitrite, and ammonium. 

In other words, the lightning strikes created the right building blocks for life.

—   Life as we know it may have its roots in an old, cold cosmic cloud  

— A baby star's planet-forming disk has 3 times more water than all of Earth's oceans

— James Webb Space Telescope spots hints of exomoons forming in infant star system

So, while lightning didn't necessarily create life, it certainly could have laid the groundwork for life to find a way.

Join our Space Forums to keep talking space on the latest missions, night sky and more! And if you have a news tip, correction or comment, let us know at: [email protected].

Space.com contributing writer Stefanie Waldek is a self-taught space nerd and aviation geek who is passionate about all things spaceflight and astronomy. With a background in travel and design journalism, as well as a Bachelor of Arts degree from New York University, she specializes in the budding space tourism industry and Earth-based astrotourism. In her free time, you can find her watching rocket launches or looking up at the stars, wondering what is out there. Learn more about her work at www.stefaniewaldek.com .

This mesmerizing NASA animation shows how carbon dioxide moves through Earth's atmosphere (video)

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• rod This idea about lightening has been discussed in 2023 too. Life on Earth quickly became independent from lightning as a nitrogen source, says new study, https://phys.org/news/2023-05-life-earth-quickly-independent-lightning.html Other sources for life origin from non-living matter is dust traps in gas clouds. https://forums.space.com/threads/the-building-blocks-of-life-can-form-rapidly-around-young-stars.67518/ Charles Darwin in 1871 postulated the warm little pond but knew that life today would eat non-living matter trying to evolve into life in that warm little pond so you could not see this take place in nature today. Apparently creating that warm little pond involves much catastrophism now when combined with astronomy and lightening strikes. Reply
• billslugg An earlier discussion noted that life's precursors might have had a boost from radiation due to elemental decay in the rocks around a seafloor vent. There was no UV down there, no high energy particles like in space. Reply
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The discovery of a new Earth-like planet could shed further light on what makes a planet habitable

Postdoctoral Researcher, Astrophysics, McGill University

Postdoctoral Researcher, Astrophysics, Western University

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The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.

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In an exciting breakthrough for astronomy and the search for extraterrestrial life, a team of international scientists has announced the discovery of Gliese 12 b , a temperate, Earth-sized exoplanet just 40 light-years away — a relatively neighbourly 378 trillion kilometres from earth.

Researchers from across the world, including key support from researchers at McGill University and Western University worked collaboratively on the hunt for Gliese 12 b within InfraRed Doppler Subaru Strategic Program (IRD-SSP) which searches for habitable zone planets around red dwarfs.

The international team detected the planet’s presence using a combination of advanced telescopes and observational techniques and its discovery presents exciting opportunities to gain a deeper understanding of the worlds beyond our own solar system.

Planet around a red dwarf

Gliese 12 b orbits around a central star named Gliese 12, which is a type of star known as a red dwarf . Red dwarfs are smaller, cooler and more abundant than the G-Type stars like our Sun.

The planets orbiting red dwarf stars are prime candidates in the search for life beyond Earth. Considerable effort has been made to find planets orbiting red dwarfs, as terrestrial worlds are easier to detect around these stars, compared to more massive stars like our Sun.

Read more: Not just space rocks: 6 things we've learned about Earth from meteorites and comets

Gliese 12 is one of two red dwarf stars — the other being TRAPPIST-1 — within 100 light-years of Earth that play host to Earth-sized planets with relatively minimal stellar radiation. TRAPPIST-1’s strong activity — such as high energy stellar flares — likely disrupts the habitability of its planets, as recent observations suggest TRAPPIST-1 b and c have almost no atmosphere .

Highly active stars exhibit more frequent and intense flares and emit life-threatening high-energy radiation than inactive stars. In contrast, Gliese 12 is an unusually inactive red dwarf, meaning its planets face much less harmful conditions.

Barely balmy starlight

What makes Gliese 12 b particularly intriguing is its size and location. It is roughly the same size as Earth, suggesting it may have similar makeup and surface environment. However, more observations and modelling are needed to confirm this.

Gliese 12 b’s location near the inner edge of its star’s habitable zone makes it especially interesting. The habitable zone, often referred to as the “ Goldilocks zone ,” is the region around a star where conditions are just right for liquid water to exist on a planet’s surface. Since water is essential for life as we know it, finding a planet around this zone is a big step in the search for life.

Gliese 12 b receives just enough starlight to be slightly closer than the inner edge of the habitable zone for red dwarfs. However, the actual presence of liquid water depends on its atmosphere and surface conditions. From another perspective, the amount of starlight it receives is between what Earth and Venus get from the Sun. Further study of Gliese 12 b could shed light on the key differences between a habitable Earth and an inhospitable Venus.

A closer look

Another exciting aspect of Gliese 12 b is that its relatively close proximity to Earth allows for more detailed study of its surface environment.

One particularly useful method for studying Gliese 12 b, which isn’t possible for non-transiting planets, is atmospheric transmission spectroscopy . This technique involves analyzing the starlight that passes through a planet’s atmosphere during transit. By studying the changes in the light’s spectra, scientists can infer the composition of the planet’s atmosphere, identifying gases like oxygen, water, methane and carbon dioxide, which could indicate biological processes.

Read more: If we want to settle on other planets, we'll have to use genome editing to alter human DNA

The discovery of Gliese 12 b is a stepping stone towards finding potentially habitable planets and understanding the conditions that make life possible. Current and future telescopes, such as the James Webb Space Telescope and ground-based extremely large telescopes, will play crucial roles in further investigations. These instruments will allow scientists to conduct more detailed studies of Gliese 12 b’s atmosphere and surface conditions.

The discovery of Gliese 12 b, a nearby possibly habitable exoplanet, is a thrilling development in the quest to find Earth-like planets and, potentially, extraterrestrial life. As we continue to explore the cosmos, each new discovery brings us closer to answering the age-old question: Are we alone in the universe?

For now, Gliese 12 b stands as a beacon of hope and curiosity, inviting us to learn more about the possibilities that lie beyond our own solar system.

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