Space questions, answered

What is the closest planet to Earth?

Venus comes closest to Earth in its orbit — but averaged over time, Mercury is the planet nearest to Earth. Surprisingly, Mercury is on average the closest planet to every other planet too.

The usual answer is Venus, because at its nearest approach it comes closer to Earth (about 38 million km) than any other planet. But 'closest' over a whole orbit is a different question: because Mercury stays near the Sun, it spends more of its time relatively near Earth than Venus does, which swings far to the other side of the Sun.

When you average each planet's distance from Earth over many years, Mercury wins. The same maths makes Mercury the closest planet, on average, to Mars, Jupiter, and every other planet in the Solar System — a result that surprises almost everyone.

See the planets' real positions in the Orrery →

Sources: Physics Today — 'Venus is not Earth's closest neighbor' (2019)