Features of the Moon

People who observe the moon usually notice two areas of the surface. One of these areas is dark-grey, and relatively smooth. These are the lunar seas often called Mares. These areas of dark grey are called the lunar seas because astronomers once thought that they were rich with water. They are actually iron-rich basaltic rock. The other areas of the moon people usually notice are the light-grey (the highlands) parts which have huge numbers of craters. These areas are made of anorthosite which is a rough-grained type of rock. Because the lunar seas are smoother, this implies that the seas are ‘younger’.

Many of the moons small craters have been made by meteoroids from around the solar system but the larger craters such as the Tycho crater and the Copernicus crater were made by asteroids.

There are some types of features on the moon such as craters, wrinkle ridges and rilles (grooves). Rilles are narrow channels in the lunar seas which can be straight or smoothly curved and are believed to have been caused by lava flows. Wrinkle ridges are caused by the buckling of the lunar surface as a result of compressive forces.