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How long is a day on Uranus?

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Images obtained by Voyager 2. — Uranus Two views of the southern hemisphere of Uranus, produced from images obtained by Voyager 2 on Jan. 17, 1986. In colours visible to the unaided human eye, Uranus is a bland, nearly featureless sphere (left). In a colour-enhanced view processed to bring out low-contrast details, Uranus shows the banded cloud structure common to the four giant planets (right). From the polar perspective of Voyager at the time, the bands appear concentric around the planet's rotational axis, which is pointing nearly toward the Sun. Small ring-shaped features in the right image are artifacts arising from dust in the spacecraft's camera.

The rotation period of Uranus, which defines the length of a day on the planet, is 17 hours and 14 minutes (17.24 hours).12

This period was determined by the Voyager 2 spacecraft, which detected radio wave emissions generated by charged particles trapped in the planet's magnetic field. Because this field is thought to originate within the planet's electrically conducting interior, this measurement is considered the rotation period of the interior itself.1

It is important to note that because Uranus lacks a solid surface, rotation speeds can vary depending on what is being observed. For instance, cloud markings in the atmosphere rotate at different speeds, ranging from 18 hours near the equator to slightly more than 14 hours at higher latitudes.1