Where exactly does the Moon flip, given that it appears the other way up in the other hemisphere?

  • I've read in multiple sources that the Moon appears the other way up in Northern Hemisphere vs Southern Hemisphere. Here is one that explains why: Does the Moon look different in the northern and southern hemispheres?

    My question is, where is the line drawn in this case where the moon 'flips'? Is it exactly the equator? I'm not sure if it is, the simple 'thought experiment' in the above link assumes (for simplicity's sake) that the orbit of the Moon is exactly above the equator. According to Wikipedia, the orbit of the Moon is slightly tilted, and our own earth also tilts from time to time. Where does the moon flip exactly? Does it change throughout the year as our earth change its tilt? If so, how? Which are the areas that always see the northern look or the southern one throughout the year?

    This happens every time the moon passes overhead. In the eastern sky, the north pole of the moon is to the left and in the western sky, the north pole is to the right.

  • barrycarter

    barrycarter Correct answer

    6 years ago

    This doesn't really answer your question, but the orientation of the moon is changing constantly, because we tend to compare the moon to the horizon, and think of the horizon as fixed. Here's a video demonstrating the effect (simulated) for the full moon over London on August 28-29 (all times GMT):


    If you were changing location, you would see a similar gradual effect.

    The only real place you would see a true "flip" is near where the moon is at zenith (overhead), because, as you passed the zenith point, the moon may go from being 89.999 degrees high in the western sky to 89.999 degrees high in the eastern sky (and flip directions because you're now comparing it to a different horizon).

    Realistically, when the moon is that high, you probably wouldn't be comparing it to the nearest horizon.

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Content dated before 7/24/2021 11:53 AM

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