A day on Uranus is 17 hours, 14 minutes and 24 seconds. In other words, a day on Uranus is shorter than a day on Earth.
One of the most bizarre things about Uranus; however, is the fact that its axis is tilted to almost 90-degrees. Unlike the other planets, which spin like tops on a table, Uranus looks like it’s rolling around. For part of the year on Uranus, the Sun appears to be move thought the sky, just like we have on Earth. But then, as the year goes on, one hemisphere is in light, and the other is in darkness for an entire season.
What this means is that a day on Uranus is the same as an entire season on Uranus. Even though the planet is rotating on its axis, the Sun will just spiral around in the sky until the planet has gone far enough around the Sun for it to be obscured. Day on Uranus is as long as Summer on Uranus, and night on Uranus is as long as winter on Uranus. Wrap your mind around that…
Windows on the Universe has got a great description of this and a handy graphic to help you imagine it. And you can get more information from the Hayden Planetarium.
We have recorded an episode of Astronomy Cast just about Uranus. You can access it here: Episode 62: Uranus.