The Hadean Eon occurred 4.6 billion to 4 billion years ago. It is named for the mythological Hades, an allusion to the probable conditions of this time. During Hadean time, the solar system was forming within a cloud of dust and gas known as the solar nebula, which eventually spawned asteroids, comets, moons and planets.
Astrogeophysicists theorize that about 4.52 billion years ago the proto-Earth collided with a Mars-size planetoid named Theia. The collision added about 10 percent to Earth’s mass. Debris from this collision coalesced to form Earth’s moon. It is hypothesized that Theia’s iron core sank to the center of the still molten Earth, giving this planet’s core enough density to begin to cool. Lighter elements “floating” on the surface began to form a scum of crustal materials. This early crust was frequently turned and subsumed by the molten interior. There are few terrestrial rocks from Hadean time, just a few mineral fragments found in sandstone substrates in Australia. However, study of lunar formations shows that the Earth/moon system continued to be bombarded by frequent asteroid collisions throughout the Hadean.
Astrogeophysicists theorize that about 4.52 billion years ago the proto-Earth collided with a Mars-size planetoid named Theia. The collision added about 10 percent to Earth’s mass. Debris from this collision coalesced to form Earth’s moon. It is hypothesized that Theia’s iron core sank to the center of the still molten Earth, giving this planet’s core enough density to begin to cool. Lighter elements “floating” on the surface began to form a scum of crustal materials. This early crust was frequently turned and subsumed by the molten interior. There are few terrestrial rocks from Hadean time, just a few mineral fragments found in sandstone substrates in Australia. However, study of lunar formations shows that the Earth/moon system continued to be bombarded by frequent asteroid collisions throughout the Hadean.
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