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The planet began to cool and for the first time in Earth's history life seemed possible. However, the earth was still being bombarded with meteorites.
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Its difficult to put a date for this given that Earth's atmosphere began developing about 4.5 billions of years ago. During this time the Earth's atmosphere began forming a homogeneous state, in which gases like hydrogen and helium were let out into space and for the first time according to our records our atmosphere held water vapor because of high temperatures in the climate. Before this time, Earth resembled more of a hell-like atmosphere with craters and no water what so ever.
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About 2 billion years ago the Earth's Oxygen levels began to rise within the atmosphere. Also, the Oklo natural fission began to finally go into operation. Again: the dates are inaccurate given that there isnt a specific date for 2 billion years ago.
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About 1.5 billions of years ago Oxygen levels reached an all time high, they are the levels that are present in todays atmosphere. Chloroplasts and Mitochondria are present. Eukariotic cells begin to form.
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About 500 to 545 millions of years ago a rise in the first fish ever in our planet began to develop.
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The quantity in Earth's oxygen began to exceed its limit. Humans begin to modify the concentrations of some gases. Also, a waxy coat of algee is developed on the Earth's surface.
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Primitive insects begin to evolve along with primitive ferns that evolve into bigger plants.
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Pangaea starts to break apart, primitive animals such as crocodiles start to wander the earth, along with an appearance of mammals throughout the planet.
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The oldest known hominid or near hominid species known as, Sahelanthropus tchadensis begins to wander the Earth's surface.
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The prokaryotes began to diverge from Archea, and chlorophyll and photosynthesis evolve in bacterial lineage. The Earth continued to release gases from the lithosphere. The water vapor clouds seemed to become more prevalent as the earth began developing.
