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 unanswered. 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.