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  • Driti Gundana

Earth

Earth was born about 4.6 billion years ago by the Big Bang just like the rest of the Solar System and the universe. The young planet had a hot molten surface that would have been death for every living being present on the planet. However, about 4.5 billion years ago, everything changed. An article about the size of the planet Mars struck the sweltering planet, tilting it 23.5º on its axis. This collision also knocked off a huge mass of the planet and formed a colossal ring around Earth. The pieces, still heated and molten, quickly came back together forming the beloved moon that we see in our night sky. This is the explanation as to why the moon’s composition is like that of Earth’s. The moon after its formation helped to stabilize the rotation of the Earth. This massive collision is one of the reasons for life’s existence on earth. If not, the Earth would be spinning upright on its axis causing the equator to heat up more than it does in the present.

The cooling down of the moon and Earth was a long and slow process. While the act of cooling was taking place, lots of changes started to take place on the planet. The sizzling and molten volcanoes erupting on Earth started to release water vapour, forming clouds. The comets slamming into the planet also brought in astonishing amounts of water that gradually filled the basins of the planet. Slowly, Earth’s surface was covered in oceans that were, on average, about 3.2km deep. Biologists also believe that life first began in these balmy and lovely oceans.

Every time landmasses were thrust up due to the volcanic activity that took place under the oceans, they began to drift and collide until they formed large landmasses, and then soon a massive supercontinent called Rodina was formed about 452 million years ago. After a while, Rodina broke down into smaller continents, and those smaller continents again collided and formed a huge landmass known as Pangea. This was about 225 million years ago. Gradually after another 94 million years, the supercontinents separated into the continents that we see today. Even today, the continents are drifting. By the next 250 million years the continents will form another huge landmass and the Pacific Ocean will cover half of Earth.

Unlike the crust of the Earth, the interior of the earth is a mystery to us. Scientists believe that the Earth consists of 4 separate layers. The place that we currently stand on, is the Rocky Crust. It is about 8 km thick under the oceans and about 72 km under the continents. The Earth is more than just that, if Earth were an apple, this crust would be about only the thickness of the peel. The temperatures under the crust are massively hot, enough to bake a pie! Just below the crust is the super sizzling mantle. Ever wondered where the ash and dust and the lava from the volcano come from, well it is from the mantle. Beneath the mantle is a liquid outer core that spins like a motor, generating a magnetic field around the Earth. It's a shield against damaging solar radiation. Finally, at the centre is the solid core. The temperature is approximately 5000 degrees C, which is about as hot as the surface of the sun!


The atmosphere of the earth consists of 80% nitrogen, and 21% oxygen along with traces of carbon dioxide, argon, water, and other element sand compounds. Too much carbon dioxide in the atmosphere would be truly corrupt for humans. Fortunately, CO2 moderates the temperature on our planet. The right amount of carbon dioxide gas keeps the planet warm by trapping the heat in the atmosphere. Without CO2 Earth would be cold for us to survive on, no matter its size, shape, or even its distance from the sun.

Unlike any other place in the solar system that we know of, the oxygen in our atmosphere is provided and replenished by living organisms. Plant life on Earth “exhales” oxygen that animals need. Without plants, there would be no animal life. It goes both ways, in turn, animals exhale carbon dioxide used by the plants during the process of photosynthesis.

Earth’s atmosphere has no definite boundary, it becomes thinner and thinner to the point where it merges with outer space. The earth’s atmosphere is divided into layers, a few of them are:

1. Troposphere- This layer is closest to the crust. It extends to about 13km into the sky. This is the layer where most weather and climate changes occur. Most planes fly in this region.

2. Stratosphere- This layer continues out for at least the next 50 km about the surface. The extremely vital Ozone Layer also lies here. The Ozone Layer consists of a very important form of oxygen, Ozone, which blocks deadly ultraviolet radiation from the sun. Without it, plants and animals would never be able to survive.

Living things are found almost everywhere on this magnificent planet, the bottom of the ocean, the equator, or even the poles. Life is everywhere. The diversity and distribution on earth are staggering. From microscopic bacteria to giant rhinoceros and electric eels to bees. Scientists have yet to catalogue all species of life existing on the planet. Taxonomists have identified about 1.2 million distinct animals and plant species, mostly mammals and birds. Nonetheless, it is said that the species of fish, fungi, insects, and land animals cross over 7 million, this is excluding bacteria.

We are not quite sure how life began on earth, but scientists know that it first began in the oceans and seas. Most living creatures carry fossil records of this past inside them. This is proven. We all know that 71% of the earth is covered with water and about 60% of our body also consists of water. Scientists think that the first life that started on the planet was bacteria, small microorganisms. In over 3.7 billion years organisms and beings have adapted to almost every environmental condition and problem thrown upon them.

Scientists and people often wonder if the same has happened on a distant planet circling different stars. Astronomers predict that possibly in the next 20- 30 years we may have the answer to the often-pondered question. Earth is a splendid and wonderful place and we should truly be grateful to it for we owe our very existence to this planet.



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