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This may be a very basic question, but I just learned that the moon orbits around the earth counterclockwise. I always thought the earth and the moon shared the rotation and orbit direction. Since the moon always shows the same face to the earth, does that mean the moon's north pole is at the bottom when I look at it from the US?

If that's the case, then in my trip to Chile when looked at the moon there... was I looking at the moon upright?

I'm not an astronomer, so it would be great to get an answer in simple terms. Thank you!

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  • $\begingroup$ cool question! $\endgroup$
    – uhoh
    Oct 15 at 23:33
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Am I looking at the moon upside down here in the US?

At latitudes greater than +/- 28.6° (let's say greater than +/- 40° to make this work easier) the Moon will always be either South or North of the zenith.

Viewing the Moon from the northern US one will always be looking in some southernly direction, unless one faces north and does a back stand to look past the zenith to see it.

  • Looking south, the Moon's northern hemisphere will be on top.

Viewing the Moon from southern Chile, say, south of Concepción, one will always be looking in some northernly direction, (again, unless doing a back stand

  • Looking north, the Moon's southern hemisphere will be on top.

Viewing the Moon closer to the equator near moonrise/moonset and facing east or west, the north and south poles will be sideways!

  • Looking east or west, the eastern or western terminator will be on top.

none of this is related to the direction of the Moon's rotation. It could start rotating the opposite way tomorrow and these wouldn't change (at least for millions of years).


How to face one way but look past the zenith in the other direction, from Ashtanga yoga, how to drop back and stand up in wheel/inverted bow

Ashtanga yoga, how to drop back and stand up in wheel/inverted bow

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    $\begingroup$ Ah, so it actually "looks" upside down above the 28-40 degrees of latitude. $\endgroup$ Oct 16 at 22:20
  • $\begingroup$ @JoeDiNottra while I didn't say that per se, basically yes! If two people at mid-latitudes in two hemispheres took photos at the same time and compared them (e.g. sent them to each other via internet) the would appear opposite. It's no different than the following: two people on the equator and the moon straight up at the zenith, they lay down on the ground with their feet touching. Each would see the Moon up-side-down compared to the other. $\endgroup$
    – uhoh
    Oct 16 at 22:38
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The Moon orbits the Earth prograde.

Looking from above the North Pole, the Earth spins counterclockwise and the Moon orbits counterclockwise. (As a result, shadows move clockwise, and the motion of clocks is based on the movement of the shadow in a sundial)

The Moon's rotation is locked to its orbit. It is tidally locked. It rotates exactly once per month. The rotation of the moon is also counterclockwise, if viewed from above the Earth's North Pole.

So no matter how you define it, the "North Pole" of the moon is on the same side as the North pole of the Earth.

But there is no "right way up". The view from Chile and from the US are equally upright. You don't see the moon upside down in the USA (but nor do Chileans)

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No, it does not.

For planets and moons, the IAU defines the north pole as the pole that shares the same half of the celestial sphere, relative to the invariable plane of the Solar System, as the Earth's north pole, so it wouldn't matter how the Moon rotated with respect to determining the Moon's north pole, just which direction that pole was pointing.

That said, both the Earth and the Moon rotate counterclockwise when viewed from above the North Pole, and the Moon orbits the Earth, and the Earth orbits the Sun counterclockwise when viewed looking down from the direction of the celestial North Pole.

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The moon does go counterclockwise around the earth (viewed from above the earth's north pole). And both the moon and the earth rotate that way too. But that means that the moon's north pole is at the top when viewed from the US, not the bottom.

You are 100% correct that, if you go to the southern hemisphere, the moon is upside down as compared to the northern hemisphere. They would probably say that it's right side up for them and upside down for us, but in any case the moon's south pole would be towards the top in the southern hemisphere.

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Some school playgrounds have bars high enough above the ground for kids to hang upsided down from if they wish. If you hang upside down from an outside bar and happen to see the Moon while doing so, you are looking at the moon (while you are) upside down.

That is the only possible way for the phrase "looking at the moon upside down" to make sense.

If you look at the Moon with your eye, the part of the Moon which looks like the upper edge to you will actually have a higher angle above the horizon than the part that looks like the lower edge to you. You will be seeing the Moon upside up.

And possibly someone in the southern hemisphere looking at the Moon will think that your lower edge is higher than your upper edge, and your lower edge will actually be farther above his horizon than your upper edge will be above his horizon. And so he will be seeing the Moon upside up from his position, even though what he sees is upside down from your position.

If you look at the Moon with the naked eye, you will see the Moon in a position which is upside up from your vantage point.

Lense and mirrors invert images. Telescopes use different combinations of lenses and/or mirrors. So if you look at the Moon though a telescope the specific combination of lenses and/or mirrors in the way the telescope is set up at the moment will determine whether the image seen thorughthe telescope is inverted or right side up.

If you are looking at the Moon though a telescope, you can glance at the Moon with your unaided eye to see if the pattern of light and dark areas is the same as though the telescope. If they are reversed, you will know that the arrangement of lens and/or mirrors in the telescope inverts the image.

And if you become familiar with the geography (selenography) of the Moon, you will be able to recognize the north and south polar regions of the Moon. Then when you look at the Moon through a telescope, or look at a photograph of the Moon taken with a telescopic lens, you will know which pole of the Moon looks "up".

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  • $\begingroup$ I should have payed more attention when in Chile. When looking with the naked eye here in the US I can recognize some light and dark areas of the moon. Heck, I think I am becoming a "selenographist". Will those light and dark areas look inverted when looked from Chile "at the exact same moment"? $\endgroup$ Oct 15 at 18:09
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The moon and earth are tidally locked. So the whole human population only gets to see one half of the moon.

P.S. Technically, due to angle differences, there will be a slight variation, but there will always be a land mass unvisited by people on earth,unless they build a spaceship, and therefore infamously called the 'Dark Side of the Moon'.

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  • $\begingroup$ Seems like you forgot to mention tidal libration, +1 anyway $\endgroup$ Oct 15 at 13:12

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