Conditions for life on earth

Earths formation was created by the big bang theory. The matter clustered together to form galaxies. The smaller material makes up the stars and the bigger material makes up the planets. 5 million years ago the solar system began to condense out of vast cloud 4 light years across. It consisted of helium and hydrogen gas. Gravity causes the cloud to collapse.

In the next 4 million years the planets collided with smaller matter to form hot molten spheres of rock. When the earth cools the water condensed on its surface (in a liquid form), forming oceans and allowing the first organisms to evolve. Most of the earth’s atmosphere was lost due to solar winds. Water vapor formed .ect. Comets in the solar system brought water and organic molecules.

 Oxygen did not appear in the atmosphere until bacteria formed. It could have also come from photosynthesis. From the oxygen the ozone could form CO2 and this blocked out…