The Composition Of The Moon
Even though much information about the composition of the
moon has been gained by studying rocks and soil brought
back by US astronauts, many questions still remain
Moon soil collected by the first Apollo astronauts was dark
gray to brownish gray in color. It consisted of tiny pieces
of ground-up rocks, bits of glass, and scattered chunks of
rock. The soil was formed by repeated grinding and churning
of the moon's surface as meteoroids hit it and flying
pieces of the moon knocked out craters.
Nothing grows or lives in moon soil. The soil contains no
plant or animal fossils. Moon rocks consist chiefly of
minerals containing aluminum, calcium, iron, magnesium,
oxygen, silicon, and titanium. Hydrogen, helium, and other
gases are trapped in some of the rocks.
Two main types of rock have been collected by the
astronauts. One type is basalt, a hardened lava and the
most common volcanic rock on the earth. The second type of
rock, called breccia, is made of soil and pieces of rock
squeezed together when hit by falling objects. The moon's
outer crust seems stiff and strong, but much remains to be
learned about its interior.
Astronauts walk easily on the moon, even though they wear
heavy equipment. They feel light because the force of
gravity on the moon's surface is six times weaker than that
on the surface of the earth.
The surface of the moon varies in temperature to a greater
degree that any place on the earth. At the moon's equator,
noon temperatures are as high as 260 degrees F. and drop
below -280 degrees F. during the two-seek lunar night. In
some deep craters near the moon's poles, the sun never
shines and the temperature is always near -400 degrees F.
The moon has little or no atmosphere. If the moon ever did
have a surrounding layer of gases, it would have leaked
away into space because of the moon's weak gravity. The
moon has no weather, no clouds, no rain, and no wind. There
is no water on its surface.
Astronauts on the moon must carry air with them to breathe
and wear space suits to protect them from the heat and cold.