History of Earth

The history of Earth concerns the development of planet Earth from its formation to the present day. Nearly all branches of natural science have contributed to the understanding of the main events of Earth's past. The age of the Earth is approximately one-third of the age of the universe. An immense amount of geological change has occurred in that timespan, accompanied by the emergence of life and its subsequent evolution.

Earth formed around 4.54 billion years ago by accretion from the solar nebula. Volcanic outgassing probably created the primordial atmosphere and then the ocean, but the early atmosphere contained almost no oxygen and so would not have supported known forms of life. Much of the Earth was molten because of frequent collisions with other bodies which led to extreme volcanism. A giant impact collision with a planet-sized body named Theia while Earth was in its earliest stage, also known as Early Earth, is thought to have been responsible for forming the Moon. Over time, the Earth cooled, causing the formation of a solid crust, and allowing liquid water to exist on the surface.