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Note - Below writeup may not be winning writing. You can write much better essays than below sample. These are just guidelines for your preparation. You can read more information and include in your essay on the day of competition.

Formation of Universe

Earth is an active place. Earthquakes rip along plate boundaries, volcanoes spew fountains of molten lava, and mountain ranges and seabed are constantly created and destroyed. Earth scientists have long been concerned with deciphering the history—and predicting the future—of mother Earth. Lets try to understand origin of Earth and later I will explain future of the Earth.

As per modern theory origin of the Earth is related to the origin of Universe. The most popular argument regarding the origin of the universe is the Big Bang Theory. It is also called expanding universe hypothesis. Edwin Hubble, in 1920, provided evidence that the universe is expanding. Based on Big Bang Theory, initially, galaxies are developed. A galaxy contains a large number of stars. Galaxies spread over vast distances that are measured in thousands of light-years. A galaxy starts to form by accumulation of hydrogen gas in the form of a very large cloud called nebula. Eventually, growing nebula develops localised clumps of gas. These clumps continue to grow into even denser gaseous bodies, giving rise to formation of stars. The formation of stars is believed to have taken place some 5-6 billion years ago. Finally, planets are formed and our mother Earth is one of the eight planet within Solar System of Milkyway galaxy.

Evolution of mother Earth

Initially planet earth initially was a barren, rocky and hot object with a thin atmosphere of hydrogen and helium. This is far from the present day picture of the earth. The earth has a layered structure. From the outermost end of the atmosphere to the centre of the earth, the material that exists is not uniform. The atmospheric matter has the least density. From the surface to deeper depths, the earth’s interior has different zones and each of these contains materials with different characteristics.

Evolution of Lithosphere

The earth was mostly in a volatile state during its primordial stage. Due to gradual increase in density the temperature inside has increased. As a result the material inside started getting separated depending on their densities. This allowed heavier materials (like iron) to sink towards the centre of the earth and the lighter ones to move towards the surface. With passage of time it cooled further and solidified and condensed into a smaller size. This later led to the development of the outer surface in the form of a crust. During the formation of the moon, due to the giant impact, the earth was further heated up. It is through the process of differentiation that the earth forming material got separated into different layers. Starting from the surface to the central parts, we have layers like the crust, mantle, outer core and inner core. From the crust to the core, the density of the material increases.

Evolution of Atmosphere and Hydrosphere

The present composition of earth’s atmosphere is chiefly contributed by nitrogen and oxygen. There are three stages in the evolution of the present atmosphere. The first stage is marked by the loss of primordial atmosphere. In the second stage, the hot interior of the earth contributed to the evolution of the atmosphere. Finally, the composition of the atmosphere was modified by the living world through the process of photosynthesis.

Evolution of Atmosphere and Hydrosphere

The early atmosphere, with hydrogen and helium, is supposed to have been stripped off as a result of the solar winds. This happened not only in case of the earth, but also in all the terrestrial planets, which were supposed to have lost their primordial atmosphere through the impact of solar winds. During the cooling of the earth, gases and water vapour were released from the interior solid earth. This started the evolution of the present atmosphere. The early atmosphere largely contained water vapour, nitrogen, carbon dioxide, methane, ammonia and very little of free oxygen. The process through which the gases were outpoured from the interior is called degassing. Continuous volcanic eruptions contributed water vapour and gases to the atmosphere. As the earth cooled, the water vapour released started getting condensed. The carbon dioxide in the atmosphere got dissolved in rainwater and the temperature further decreased causing more condensation and more rains. The rainwater falling onto the surface got collected in the depressions to give rise to oceans. The earth’s oceans were formed within 500 million years from the formation of the earth. This tells us that the oceans are as old as 4,000 million years. Sometime around 3,800 million years ago, life began to evolve. However, around 2,500-3,000 million years before the present, the process of photosynthesis got evolved. Life was confined to the oceans for a long time. Oceans began to have the contribution of oxygen through the process of photosynthesis. Eventually, oceans were saturated with oxygen, and 2,000 million years ago, oxygen began to flood the atmosphere.

Origin of Life

The last phase in the evolution of the earth relates to the origin and evolution of life. Modern scientists refer to the origin of life as a kind of chemical reaction, which first generated complex organic molecules and assembled them. This assemblage was such that they could duplicate themselves converting inanimate matter into living substance. The record of life that existed on this planet in different periods is found in rocks in the form of fossils. The microscopic structures closely related to the present form of blue algae have been found in geological formations much older than some 3,000 million years. Following are milestone stages of origin of life on Earth.

Origin of the universe (12000 Million ago)

Origin of the sun

Oceans and Continents

Blue green Algae: Unicellular bacteria

Soft-bodied arthropods

No terrestrial Life: Marine Invertebrate

First Fish

First trace of life on land: Plants

Amphibians

First Reptiles: Vertebrates: Coal beds

Reptile dominate-replace amphibians

Frogs and turtles

Age of Dinosaurs

Extinction of Dinosaurs

Small Mammals: Rats – Mice

Rabbits and Hare

Anthropoid Ape

Ape: Flowering Plants and Trees

Early Human Ancestor

Homo Sapiens

Modern Man (10000 years ago)

Civilization:

Throughout more than 90% of its history, Homo sapiens lived in small bands as nomadic hunter-gatherers. As language became more complex, the ability to remember and communicate information resulted. Ideas could be exchanged quickly and passed down the generations. Cultural evolution quickly outpaced biological evolution, and history proper began. Between 8500 and 7000 BC, humans in the Fertile Crescent in the Middle East began the systematic husbandry of plants and animals. This spread to neighboring regions, and developed independently elsewhere, until most Homo sapiens lived sedentary lives in permanent settlements as farmers. Civilizations adopted agriculture allowed the population to expand. Agriculture had a major impact; humans began to affect the environment as never before. Surplus food allowed a priestly or governing class to arise, followed by increasing division of labor. This led to Earth's first civilization at Sumer in the Middle East, between 4000 and 3000 BC. In 1492, Christopher Columbus reached the Americas, initiating great changes to the new world. European civilization began to change beginning in 1500, leading to the scientific and industrial revolutions.

Impact of industrial revolution

It is widely recognized that Earth’s mean global surface temperature has risen since the beginning of the industrial age, and that emissions of CO2 and other greenhouse gases are at least partly responsible. The potentially serious consequences of global warming underscore the need to determine how much of the warming is caused by human activities and what can be done about it. Earth science has an important role in answering both questions. The geological record has revealed the history of the planet’s climate to be a peculiar combination of both variability and stability. Global climate conditions have been favorable for life and relatively stable for the past 10,000 years and suitable for life for over 3 billion years. But geological evidence also shows that momentous changes in climate can occur in periods as short as decades or centuries. How does Earth’s climate remain relatively stable in the long term, even though it can change so abruptly? Understanding periods in which the planet was extremely cold, extremely hot, or changed especially quickly are leading to new insights about Earth’s climate. Observations of ancient rocks could eventually improve prediction of the magnitude and consequences of climate changes.

Future of Mother Earth

Mother Earth is clearly urging a call to action. Nature is suffering. Australian fires, heat records and the worst locust invasion in Kenya. Now we face COVID -19, a worldwide health pandemic link to the health of our ecosystem. Climate change, man-made changes to nature as well as crimes that disrupt the mother Earth's ecosystem. If none of that gets us, the Sun will. Our home star bathes us in light, and supplies the energy for almost all the life on Earth. But it won't be friendly forever. As we saw earlier, the Sun is gradually getting hotter. Eventually it will be hot enough to evaporate all Earth's oceans, and cause a runaway greenhouse effect that sends temperatures soaring upwards. This process might begin in about a billion years, and would wipe out all. But that's not all. Beginning around 5 billion years from now, the Sun will expand, becoming a swollen star called a red giant. By 7.5 billion years in the future, its surface will be past where Earth's orbit is now. So the expanding Sun will engulf, and destroy, the Earth. It's been suggested that Earth might escape. The Sun will lose mass as it grows, so Earth will spiral further out. If any humans are still around, they might have the technology to move the Earth to safety. Otherwise, life on Earth has a maximum life expectancy of 7.5 billion years.

I conclude my essay with following thought -

Sooner or later, we will have to recognise that the Earth has rights, too, to live without pollution. What mankind must know is that human beings cannot live without Mother Earth, but the planet can live without humans. - Evo Morales

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