The Moon has nothing to speak of in the way of atmosphere, it appears to be geologically inactive. We also now suspect
that the Moon, unlike the other natural satellites, was formed after a catastrophic collision with the early Earth. The process of
formation may have looked like this. What evidence is there of this collision?
The Apollo Moon Program gathered a large amount of data from the Moon.
Radius of the Moon: 1738 km
The Moon is approximately 1/4 the radius of the Earth. It’s
mass is 81 times less. That gives us the result that the
Moon is not the same density as Earth. It is not made of the
same stuff. We now know that the Moon has little heavy
metals such as iron. It is pretty much rock, right to the
center.
Rotation of the Moon:
The Moon does spin once in 27.3 days. You should know
that we only see one side of the Moon from Earth. How can
that be if the Moon is rotating (spinning)? The answer is
that it spins as fast as it orbits. Virtually every other moon
in our solar system does the same thing. We say they are
tidally locked. These moons always face their central planet
as they circle around.
Orbit of the Moon: 27.3 days
The Moon orbits the Earth once in 27.3 days. This is the
same rate that it spins. Virtually every other moon in our
solar system does the same thing. We say they are tidally
locked. These moons always face their central planet as
they circle around.
Atmosphere of the Moon:
The Moon does have a very tenuous atmosphere with some
odd components..