Earth,the 3rd planet in our Solar System.The only planet to have life on it was an dust cloud 5 billion years ago with no existence of land, air and water.So how this cloud transformed into blue green marble we know as Earth.Why scientist say that the newborn Earth(Proto Earth or Raw Earth) was 4 times smaller and thousand times hotter than today's Earth.If Raw Earth was so small,how it got so much mass. And if It was so much hot, then how it cooled to support life.So let's see Earth's biography.
Ans.There are many hypothesis(theory) on how Earth was formed.But the logical hypothesis is "Solar Nuclear Disk Model"(SNDM).This theory was made by Pierre Simon Laplace (1749-1847).So let's start.
According to SNDM, around 6 billion years ago, instead of our of our Solar System there was an dust cloud called Nebula. Nebula mainly contains-dust, hydrogen and other ionized gases.Nebula are made from remains of Stars and Black Holes. By the time the matter increased in nebula because increased mass means increased gravity.Due to increased gravity nebula started forming in spherical shape. Beside nebula there was a star that went in supernova stage. It is a stage of stars, in which massive stars end their lives with a massive explosion. The shock wave from star removed the gravity of the nebula. because of no gravity, spherical nebula was transformed into flat disk shaped Nebula. The shock wave also gave nebula Angular Momentum(rotational energy).Without center of gravity, matter got unevenly distributed in the disk. Where the matter was dense,there more matter gathered because of gravitational full.Due to this the, surface area of the nebula disk reduced. reduced surface are means more speed in angular momentum.When angular momentum increased, it created a vortex in center of nebula. Then vortex started pulling matter in center of nebulae. After some time there was so gathering of matter in center,it started producing heat. By the time heat increased and increased. But the the vortex was actually creating a baby sun. This baby sun is called ProtoStar. So the protostar's gravity started pulling remains of nebula towards it.So it created a disk around sun called ProtoPlanetery Disk. But all this happened suddenly?. No, this all took many millions of years. In ProtoPlanetery Disk, there were mainly 3 elements. They are metal,silicates and gases.Because metal and silicates are dense,they started revolving around the ProtoStar. Gases were less dense,so they started revolving far from ProtoStar, they were also very large in amount. By the time ,due to gravitational pull they formed into planets. Metal and silicates formed rocky or terrestrial planets and gases formed gas giants.Totally they formed our solar system with 9 planets. You'll think it's a typing mistake, but it's not. The terrestrial planets are-Mercury,Venus,Earth,Mars and Theia. The Gas Giants are- Jupiter, Saturn, Uranus, Neptune. Theia was a planet size of Mars. At that time Earth was 4 times smaller. But due to Gravitational pull of Theia, It collided with Earth and fused. But collision's debris flew and formed the lump we know as Moon. Now Earth mass was very much increased to handle 7.7 billion people. Now increased mass of Earth made increased gravity. Due to gravity, Earth started pulling asteroids. This made Asteroid Bombardment on Earth. This made Earth thousand times hotter than today's Earth. After some years, when Asteroid Bombardment stopped, life got a chance to born.From here first life started.
Video on this topic-
How was the Solar System formed?
No comments:
Post a Comment