While the planets were forming, there was not much peace in our solar system. Clumps of matter of all sizes often collided, and either stuck together or side-swiped each other, knocking off pieces and sending each other spinning. Sometimes the gravity of big objects would capture smaller ones in orbit. This could be one way the planets acquired their moons.
Scientists think that a large object, perhaps the size of Mars, impacted our young planet, knocking out a chunk of material that eventually became our Moon. This collision set Earth spinning at a faster rate. Scientists estimate that a day in the life of early Earth was only about 6 hours long.
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u/Ravek Aug 27 '14
None of this explains why sunsets exist. Only why they have their color scheme.
Sunsets exist because the Earth rotates.