Moonquest! The Adventure Begins)
Like the rest of the Solar
System, the Moon is about 4 1/2 billion years old. Most of the cratering
occurred in the first billion years of its life, when leftover debris from
planet formation was abundant.
The same side of the Moon
always faces the Earth. (The Moon's rotation period is synchronous with
its revolution period around the Earth).
Because of a loss of orbital
energy to gravity from the Earth, the Moon is very gradually moving away
from the Earth. In the early history of the Earth, the Moon looked about
3 times larger in apparent size in the sky, because it was closer to the
The dark looking "seas" on
the Moon are really smoother and darker colored rock that came from volcanic
flows early in the history of the moon after most of the cratering had
occurred. These dark spots are called "Maria".
There are few "seas" on the
back (far) side of the Moon (the side opposite Earth).
The Moon is only one-fourth
the diameter of the Earth.
The Moon has almost no atmosphere,
because of its weak gravity. All types of gas will escape from its surface.
The surface temperature fluctuates from roughly + 300° F during the
2-week daytime to -270 F during the 2-week night. This is because
there is not enough atmosphere to keep the Moon warm at night, nor protect
it from the Sun's rays in the daytime.
Without an atmosphere, there
is no wind or water erosion. The Moon's surface is about the same now as
it was 3 billion years ago. (Contrast to the Earth). The astronauts' footprints
remain unchanged on the Moon's surface, and will until the Moon is struck
by an asteroid.
Want to find
about the Moon? Check out some of these links...
Star Child: Level
One and Level
Moon - from Windows to the Universe
Asked Questions about Lunar Prospector and the Moon
to the Moonquest page