If you stand on top of the sun, and one foot off of the surface so that you don't rotate with the sun, while wearing the calendar watch you bought on Earth . . .
. . . the Sun rotates under your feet about once a month;
. . . you see the Earth revolving around you once a year;
. . . you see the Moon revolving around you once a year, and ALSO wiggling slightly in and out, slightly nearer and farther from you. When it's nearer, it's slightly nearer to you than the Earth is. When it's farther, it's slightly farther from you than the Earth is. About half of the wiggle, it's slightly to the left of the Earth, ahead of the Earth in its orbit. The other half, it's slightly to the right of the Earth, behind the Earth in its orbit. The Moon goes through a complete one of these near-and-far wiggles every 27.3 days.
If you stand on top of the Earth, and one foot off the ground so that you don't rotate with the Earth . . .
. . . the Earth rotates under your feet about once every 24 hours;
. . . you see the Sun revolving around you once a year;
. . . you see the Moon revolving around you once every 27.3 days. The Moon is also rotating, but it takes exactly the same 27.3 days to rotate once, so it ends up keeping the same side facing you all the time, and you can never see anything on the other side.
If you stand on top of the Moon, one foot off of the surface so that you don't rotate with the Moon, while wearing the same calendar watch that you bought on Earth . . .
. . . the Moon rotates under your feet, about once every 27.3 days;
. . . you see the Earth revolving around you at exactly the same rate, about once every 27.3 days, so that if you look down at the Moon beneath your feet, you notice that the same side of it is always facing the Earth, and the other side of the Moon can never see the Earth.
. . . you see the Sun revolving around you once a year.
