the gravitational pull of the planet it orbits
gravity
Angular momentum holds up the moon.
Actually, the planets are all constantly moving. They have a gravitational attraction to each other, though.
One moon joke would be: What holds the moon up? Answer: Moonbeams.
The Earth's gravity holds the Moon in its orbit.
The force that holds the moon in place is gravity. Without gravity, there wouldn't be a moon.
gravity
Angular momentum holds up the moon.
The force of mutual gravitational attraction. We know THAT it works, but we don't know how. Yet.
Actually, the planets are all constantly moving. They have a gravitational attraction to each other, though.
One moon joke would be: What holds the moon up? Answer: Moonbeams.
The Earth's gravity holds the Moon in its orbit.
The moon maintains its orbit due to the balance between the earth's gravity and the moon's inertia.
The gravity of its planet.
the earths gravity holds the moon so it orbits the earth.
It is not presently known for certain that the moon causes earthquakes, but it is likely that the moon does have, at least, some effect. The moon has gravity of its own, and the pull of this gravity reaches out to earth as the moon orbits the earth, reducing the effect of earth's gravity over the portion of the earth that is directly under a moon. Earth's gravity is what holds the planet together -- it holds the atmosphere in place, the oceans on the crust, the crust on the mantle and keeps the mantle and core in place. This small but continuous tug on the Earth can cause resettling and friction within the earth, which can create earthquakes, especially in constant motion as the Moon is in orbit of the earth. The Moon has quakes of its own (the Apollo program left seismology instruments on the Moon to measure this), and it is believed some of the deep moonquakes are caused by Earth's tidal effects on the Moon.
The orbital path of the moon and gravitational attraction between the moon and the earth keep it up there where it is supposed to be.