Scientists have been able to reconstruct detailed information about the planet's past. Earth and the other planets in the the solar system formed 4.54 billion years ago out of the solar nabulo , a disk-shaped mass of dust and gas left over from the formation of the Sun. Initially molten, the outer layer of the planet Earth cooled to form a solid crust when water began accumulating in the atmosphere. The Moon formed soon afterwards, possibly as the result of a Mars-sized object (sometimes called theia) with about 10% of the Earth's mass impacting the Earth in a glancing blow.Some of this object's mass would have merged with the Earth and a portion would have been ejected into space, but enough material would have been sent into orbit to form the moon.
Outgassing and activity produced the primordial atmosphere. Condensing water, augmented by ice delivered by The highly energetic chemistry is believed to have produced a self-replicating molecule around 4 billion years ago, and half a billion years later.
The development of allowed the Sun's energy to be harvested directly by life forms; the resultant accumulated in the atmosphere and resulted in a layer of (a form of in the upper atmosphere. The incorporation of smaller cells within larger ones resulted in the True multicellular organisms formed as cells within colonies became increasingly specialized. Aided by the absorption of harmful by the , life colonized the surface of Earth.As the surface continually reshaped itself, over hundreds of millions of years, continents formed and broke up. The continents migrated across the surface, occasionally combining to form . Roughly 750 million years ago (mya), the earliest known supercontinent, , began to break apart. The continents later recombined to form , 600–540 mya, then finally , which broke apart 180 myaSince the 1960s, it has been hypothesized that severe action between 750 and 580 mya, during the , covered much of the planet in a sheet of ice.
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