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Which Planet Has the Longest Day? Planet Day Lengths Compared

Venus has the longest day in the solar system

Venus has the longest day of any planet in the solar system when you measure a full rotation on its axis. Its rotation is so slow that one day lasts longer than one Venus year.

Planet Day Length Comparison

PlanetDay LengthWhy It Stands Out
Mercury1 Mercury day = 58.6 Earth daysOne solar day on Mercury lasts 176 Earth days.
Venus1 Venus day = 243 Earth daysVenus rotates so slowly that one day is longer than one Venus year.
Earth1 Earth day = 24 hours exactlyEarth is the baseline for the comparison table: one day is exactly 24 hours.
Mars1 Sol = 24h 37m (×1.027 Earth)Mars keeps a near-Earth rhythm with a Sol of 24 hours 37 minutes and 22 seconds.
Jupiter1 Jupiter day = 9h 55m (×2.4 Earth)Jupiter has the shortest day of any planet in the solar system.
Saturn1 Saturn day = 10h 42m (×2.25 Earth)Saturn spins quickly enough to make it the most oblate planet in the solar system.
Uranus1 Uranus day = 17h 14m (×1.39 Earth)Uranus rolls on its side, which makes its seasonal timing unusually extreme.
Neptune1 Neptune day = 16h 7m (×1.49 Earth)Neptune rotates in 16 hours 7 minutes and has fierce winds driven by internal heat.

The Short Answer

Venus has the longest day of any planet in the solar system when you measure a full rotation on its axis. Its rotation is so slow that one day lasts longer than one Venus year.

How Long Is a Day on Venus?

Venus rotates very slowly and in the opposite direction from most planets. Its day length is 243 Earth days, which is much longer than the 225 Earth days it takes to orbit the Sun.

Why Venus Rotates So Slowly

The exact reason Venus rotates so slowly is still debated. Early impacts, tidal effects, and atmospheric interactions may all have played a role in shaping its unusual spin.

How Other Planets Compare

The comparison table shows how quickly the other planets spin. Jupiter is the fastest-rotating planet, while Venus sits at the opposite extreme.

Longest Day vs Shortest Day

Venus has the longest day, and Jupiter has the shortest day. Seeing them side by side makes the range of planetary time in the solar system easy to understand.

Frequently Asked Questions

Which planet has the shortest day?

Jupiter has the shortest day in the solar system.

How long is a day on Venus?

A full rotation on Venus lasts 243 Earth days.

Why are planetary days different?

Each planet formed with a different rotation rate, and later gravitational interactions changed some of those spins.

Is a day always shorter than a year?

No. Venus is the best-known example where one day is longer than one year.

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