Online Astronomy eText: The Planets / The Sky
The Rotation of Uranus Link for sharing this page on Facebook
(partial discussion)
The Rotation Period and Day Length for Uranus
      Uranus rotates once every 17 hours 14 minutes 24 seconds, as determined from the rate of rotation of its magnetic field. (Various portions of its atmosphere rotate around the planet as much as an hour faster or slower than this, depending upon their direction and speed of motion relative to the overall rotation of the planet.)
      As discussed at Rotation Period and Day Length, the rotation period given above, which is the sidereal period of rotation of the planet (the time it takes to turn once around relative to the stars), differs by about one second from the length of its day (the time it takes the Sun to move once around the sky), due to Uranus' orbital motion during one rotation. Because the planet has a retrograde or backwards rotation relative to its orbital motion, its day is shorter than its rotation period (for the Earth, which rotates in the same direction it orbits the Sun, the day is longer than the rotation period). The rotation period of Uranus is therefore about 17 hours 14 minutes 23 seconds.

The Axial Inclination for Uranus
      The axis of Uranus' rotation is tilted more relative to the pole of its orbit than that of any other planet, differing by 97.7 degrees if the rotational direction of the planet is used to define its north pole, or (as noted at Seasons on the Other Planets) by 82.2 degrees if the north side of our orbit is used to define the planet's north pole. According to the traditional definition based on the direction of the planet's rotation, Uranus' south pole faced the Sun in the 1980's, when Voyager 2 passed by it; but using the more modern definition based on the rotation of the Earth, Uranus' north pole faced the Sun at that time (this can obviously cause confusion in reading different discussions of the planet's rotation).
      Uranus' pole points toward (approximately) RA 17:09:15, Dec S 15:10:30, which is in the constellation Ophiuchus, not far from Eta (η) Ophiuchi, or Sabik.

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