The only planet in our solar system whose day is longer than its year is Venus.

Here's why:

* Venus's rotation is retrograde: It spins on its axis in the opposite direction of most other planets in our solar system.

* Extremely slow rotation: Venus takes about 243 Earth days to complete one rotation.

* Short orbital period: Venus orbits the Sun in about 225 Earth days.

Therefore, a day on Venus (one complete rotation) is longer than a year on Venus (one complete orbit around the Sun).