A simple experiment

  • Thread starter Phobos
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  • #1
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Before my rush to work this morning, I was at the gas pump enjoying a splendid view of New England Fall foliage with a waning gibbous moon suspended low in the sky. The declination of the Moon was such that I could adjust my line of sight so that the Moon appeared just above the top the gas pump. Over the next minute or so, standing very still, I watched the moon sink below my artifical horizon. By adjusting my line of sight, I watched the moon set several times.

A simple, yet elegant reminder that we're standing on a rapidly spinning globe and that the seemingly still astronomical sky is actually marching right along at quite a good clip.

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  • #2
Science Advisor
If you want more "proof-positive" of the real rotation rate of Earth, then try looking at an object in an undriven telescope at 250X and above. I do it, but it takes a fair amount of practice, and glass-smooth bearings in both axes.