ASTR 103 Lecture Notes - Lecture 8: Anorthosite, Space Debris, Meteoroid
Document Summary
The moon and earth both orbit around a point between their centers, called the center of mass, of the earth-moon system. The moon"s airless, dry surface is covered with plains and craters. The earth-facing side of the moon displays light-colored, heavily cratered highlands and dark-colored, smooth-surfaced maria. Virtually all lunar craters were caused by space debris striking the surface. The maria formed after the surrounding light-colored terrain, so they have not been exposed to meteoric bombardment for as long and have fewer craters. Much of our knowledge about the moon has come from human exploration in the 1960s and 70s and from more recent observations by unmanned spacecraft. Meteoroid impacts have been the only significant erosion agent on the moon. The moon"s regolith or surface layer of powdered and fractured rock, formed by meteoritic action. All of the lunar rock samples are igneous rocks formed largely of minerals found in terrestrial rocks.
