Averaged over time, the planet closest to Earth is Mercury.
Venus comes nearer at its best, but spends most of its orbit on the far side of the Sun — and Mercury is the nearest neighbour to every other planet too.
Source
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More space facts
Space facts are where the numbers stop making sense. A total eclipse only works because the Sun is 400 times wider than the Moon and 400 times further away. Venus spins backwards, some of the static on an old TV was the Big Bang, and almost all of the universe is missing. Every fact here links to its source.
- A total eclipse is an astonishing coincidence.
- Some of the static on an old TV was the Big Bang.
- Almost all of the roughly 1,500 injuries from the 2013 Chelyabinsk meteor came from flying glass.
- Almost all of the universe is missing.
- Astronomers aimed a telescope at an empty patch of sky for ten days.
- Every atom in you heavier than iron came from a dying star.