Which planet spins the fastest and which the slowest?

Jupiter is the fastest spinning planet in our solar system rotating on average once in just under 10 hours. That is very fast especially considering how large Jupiter is. This means that Jupiter has the shortest days of all the planets in the solar system.
Venus is the slowest - it rotates once every 243 days —- by far the slowest rotation period of any of the major planets. A Venusian sidereal day thus lasts more than a Venusian year (243 versus 224.7 Earth days). However, the length of a solar day on Venus is significantly shorter than the sidereal day; to an observer on the surface of Venus the time from one sunrise to the next would be 116.75 days.

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