What Landforms Are on the Moon?

Regions

• Even without a telescope, most people can see that the Moon consists of dark gray areas on a lighter background. The darker areas are called maria, or seas, because early astronomers mistakenly believed these areas were covered by water. The lighter areas are mountainous regions called highlands.The mountains in this area can reach heights of 25,000 feet but they aren't very steep. The highlands are the older sections of the lunar crust and made of feldspar, a crystalline material that formed in the magma that covered the Moon shortly after its formation about 4.5 billion years ago. The seas are the youngest sections of the crust and primarily consist of basalt, or igneous rock created from magma.

Upper Surface

• The moon's upper surface is covered in a thin layer of soil called "regolith," primarily consisting of lunar rocks that were ground up and melted when the Moon was bombarded with meteorites. The soil consists of cobble, pebble and boulder-sized lunar rocks and material from the meteorites. The regolith is exposed to the solar wind and cosmic radiation so it contains materials such as hydrogen that are prevented from reaching Earth's surface by the planet's atmosphere and magnetic fields.

Craters

• The highlands are dotted with impact craters from numerous meteorite strikes between 4.5 and 3.9 billion years ago. These craters are circular depressions featuring central peaks and surrounded by walls. They can range in size from just a feet across to several miles. In some regions they are so many craters that they overlap. Some large craters even have smaller craters inside of them. The seas also have craters, however, not as many as are found in the highlands.

Formation

• Before the Apollo missions occurred, scientists had many theories about the Moon's origin. One suggested that the Moon and Earth formed as a double planet while another suggests that it was captured by the Earths gravity. Scientists now believe the Moon formed about 4.5 billion years ago from material that broke away from the primitive Earth when it was hit by an object about the size of the Moon or Mars. Many scientist believe this explains several features of both the Moon and the Earth such as the Moon's chemistry and the tilt of the Earth's axis.