Which planet in the Solar System has the shortest year?

Mercury has the shortest year of any planet in the Solar System, completing an orbit around the Sun in about 88 Earth days.

Mercury is the innermost planet, so its smaller orbit gives it the fastest orbital period. It travels around the Sun at an average distance of about 58 million kilometres. Despite its short year, Mercury rotates slowly: one solar day on the planet lasts about 176 Earth days.

Mercury is the smallest planet and has no substantial atmosphere to retain heat. Temperatures therefore vary dramatically between its sunlit and dark sides. Venus has the longest rotation period of any planet, but not the longest year; its orbit takes about 225 Earth days. Mercury’s fast orbit should not be confused with its rotation, which is much slower and linked to a distinctive 3:2 spin-orbit resonance.