Re: How would the Earth look to a person living on the moon?

Hi, Debbie! Sorry if the answer I give below is a
little complex: try looking at a model of the Earth-moon system
to help understand it, or even just try having two apples "orbit
around" each other to help visualize what I'm about to say...

If you follow the moon through all its phases each month, you may
notice that the same side of it is always facing us here on Earth:
because the moon rotates with EXACTLY the same period as it orbits
the earth, Earth only gets to see one side of the moon's globe.
(The side Earth never gets to see is called the Far Side: if you
stood on the Far Side, you'd never see Earth at all of course!)

Since the same side of the moon is always facing us, the amazing
thing is that the Earth doesn't rise or set as seen from most of
the moon! It merely sits in the sky in much the same place every
month, going through its own (much brighter) phases: when we see
the moon as brand new, inhabitants of the moon's Near Side would
see Earth as a bright, full disk! When we see the moon as in the
"gibbous" phase (between half and full), Earth will appear to be
a crescent to a moon-walker. And most amazing of all, during a
"total lunar eclipse" (when the earth passes in front of the full
moon and blocks out the light from the sun), Lunar residents get
to see Earth as a black spot in the sky, blotting out the sun,
but surrounded by a bright red disk of refracted sunlight!

Now there ARE certain places where the Earth sits so close to the
lunar horizon, that even though it only moves in a tiny circle in
the lunar sky each month, it DOES rise and set - all or partway.

This is because the moon rotates on its axis at a constant rate,
but doesn't ORBIT at a constant rate! Instead, it moves a little
bit faster during parts of its orbit (near "perigee", when it is
closest to Earth) and a little slower during other parts (near
"apogee", when it's furthest out). So, if you were standing near
the western or eastern "edge" of the moon (as seen from Earth),
Earth would sit right near your horizon, and would actually dip
down below it for 14 days or so of the 28-day lunar "year".

By the same token, the moon's orbit is slightly out of the plane
of its rotation, and so if you were standing at either Pole of
the moon, you'd also see Earth right at your horizon for 14 days
more or less, and actually below the horizon the rest of the time.

This monthly "wobbling" of the moon as seen from Earth (or the
Earth as seen from the moon!) is called "lunar libration".

(Coincidentally, the fact that the moon's rotation period is the
same as it's orbital period is due to the Earth's very strong
gravitational pull on the moon, and to a slight imbalance in the
moon's internal mass: in effect, the Near Side of the moon is
"heavier" than the Far Side, so Earth's powerful gravity always
keeps the Near Side yanked toward us.)