A Single Day on Mercury Lasts Twice as Long as Its Own Year
Mercury orbits the Sun in just 88 Earth days, yet one full sunrise-to-sunrise day on its surface takes 176 Earth days.
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Interactive Scenemercury planet sun
🪐 Cosmic Discovery
NASA Solar System Exploration
Key Metric+20 XP
How many Earth days does one solar day last on Mercury?
Your guess:0 Earth days
Key Insight
Rotating three times for every two orbits makes the Sun appear to move across Mercury's sky very slowly.
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Cosmic Discovery
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Why / How?
01
Scientific Mechanism
Mercury is locked in a 3:2 spin-orbit resonance, rotating three times on its axis for every two orbits around the Sun, stretching its solar day to two full years.
02
Why It Matters
Rotating three times for every two orbits makes the Sun appear to move across Mercury's sky very slowly.
Verified Source
NASA Solar System Exploration