Planets by Length of Day

About This Dataset

This chart compares how long a full day lasts on each planet of the Solar System, measured in Earth hours from one sunrise to the next. Jupiter has the shortest day at under 10 hours, while a single day on Venus lasts 2,802 hours - about 117 Earth days.

Analysis

Planet size and day length are strikingly mismatched: Jupiter, the largest planet, spins fastest with a 9.9-hour day, while small Venus takes 2,802 hours - the slowest rotation in the Solar System, and it even spins backwards relative to the other planets. The gas giants all rotate quickly (10 to 17 hours), a leftover of the angular momentum they hoarded while forming, and their speed is what flattens them visibly at the poles. Among rocky planets, Earth and Mars are near-twins at 24 and 24.7 hours, one reason Mars mission planners can keep crews on an almost-normal schedule. Mercury's 4,222-hour day means one Mercury day outlasts its own year, which takes only 88 Earth days.

Source: NASA Planetary Fact Sheet

Key Findings

🏆

Mercury leads in Length of Day (Earth Hours) with 4,222.60.

📊

Average Length of Day (Earth Hours): 891 · median: 20.60.

↔️

Gap: Mercury is 426.5× larger than Jupiter.