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Which Planet Has the Longest Day?

SpaceAstronomy

Quick Answer

Venus has the longest day of any planet in our solar system: one Venusian day (sidereal rotation) is about 243 Earth days.

The Full Story

Venus rotates so slowly that one full rotation on its axis takes about 243 Earth days — longer than its year (225 Earth days). This means a sidereal day on Venus is longer than a Venusian year. Even more unusually, Venus rotates in the opposite direction to most planets (retrograde rotation), so the Sun rises in the west and sets in the east. Because of this retrograde spin, a solar day (noon to noon) on Venus is shorter than its sidereal day: about 117 Earth days. The slow rotation may be caused by tidal interactions with the Sun and its dense atmosphere.

Key Facts

1.Venus rotates once every 243 Earth days but orbits the Sun in 225 days, making its day longer than its year.
2.Mercury has the second-longest solar day at about 176 Earth days.
3.Jupiter has the shortest day of any planet: just under 10 hours.

YouTube Angle

Suggested video title for this topic:

"Venus — The Planet Where a Day Is Longer Than a Year"