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4600 BCE
Planet Accretion (4.6 Billion years ago)
Material accumulates to form each of the planets in the Solar System -
4500 BCE
Core Formation
Heavier materials such as Iron and Nickel cool in the center. -
Period: 4500 BCE to 3800 BCE
Planetary Cooling
Earth forms into a molten planet; asteroids and meteors helped shape it into a sphere -
Period: 4100 BCE to 3800 BCE
End of Heavy Bombardment
Asteroids and smaller protoplanets impact the larger planets. During the Late Heavy Bombardment, the number of impacts may have increased