I drew the above to try and make sense of why we see the moon as different stages of fullness. So the circle in the center with an “N” in it is like a bird’s eye view of earth, looking down on the north pole (earth rotates counterclockwise around the sun and spins around its own axis counterclockwise). The same face of the moon is always facing the earth.
The top circles represent the moon’s position at sunset over its 28 days in relation to both the sun and the earth. The same face of the moon is always facing the earth, so the half illuminated by the sun changes.
The bottom set of circles represents the moon as it appears to us at night when it’s in each of those positions.
Again, each night the moon falls behind the earth’s rotation by about 52 minutes or so, so the
If the moon didn’t shift its rotation slightly each night (that arc across the sky shown in the top photos) then we’d have a lunar/solar eclipse every full/new moon, respectively.
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| Overlay of first photo, with another, taken Thursday morning at 12:06am, showing the moon roughly at the same height, but further south |
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| Taken Friday morning at 12:20am |
This is bringing up as many (well lots more) questions as answers. I feel like I’m starting to make sense of it all, but I can see that to truly understand how fickle the moon is I’d need to watch her for a lot longer than a few weeks.
