While it might seem counterintuitive, Venus has the slowest rotation period of all the planets in our solar system, taking about 243 Earth days to complete one rotation. This is even slower than its orbital period around the Sun, which is 225 Earth days.

Here's a breakdown of the rotation periods of the outer planets:

* Jupiter: 9.9 hours

* Saturn: 10.7 hours

* Uranus: 17.2 hours

* Neptune: 16.1 hours

* Venus: 243 Earth days

So, even though Venus is closer to the Sun than the other outer planets, it rotates much slower, resulting in the longest day in our solar system.