Early bombardment phase
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The early bombardment phase was a period early in the history of the solar system where the rubble and debris from the Sun's formation had not yet cleared.
This phase lasted from four billion to nearly three billion years ago. It is characterised by frequent heavy impacts on all planets which are capable of holding such record (such as Mars, Mercury and our Moon). The rise of life on Earth occurred around the time this heavy bombardment ended.
Some theories include this phase as delivering much of Earth's water.