• brianorca@lemmy.world
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    11 months ago

    Mercury orbits the sun every 88 earth days. It spins on its axis every 59 earth days, relative to an outside observer (sidereal day.) That makes the solar day (from sunrise to sunrise) 179 earth days long.

    • kase@lemmy.world
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      11 months ago

      So in a certain sense, a ‘day’ on Mercury is 2.034090909090 ‘years’ long? (Solar day divided by orbiting the sun, lol)

      • brianorca@lemmy.world
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        11 months ago

        No. I rounded off the numbers. A Mercury day is exactly 2 Mercury years. Which is why it’s “in resonance”. That means that gravity will speed up or slow down the rotation to keep the ratio stable over time.