Physical Features of the Earth & Moon

Similarities

• The Earth and moon share many physical features. This is because they were once the same planet until the moon was blasted off the Earth by a Mars-sized impactor. The impactor theory explains why the Earth and its satellite are made of rocks with similar mineral compositions. Basaltic moon rocks of plagioclase feldspar and olivine have the same chemistry as Earth rocks. Both rocky celestial bodies are organized into divisions of core, mantle and crust structures.

Differences

• Moon soil has no organic material and very little water when compared to Earth dirt. Moon soil has been pulverized into tiny particles by meteorites. The moon is geologically dead, with little erosion, while the Earth is characterized by tectonic activity, resulting in uplifted mountains. The moon's mountains were raised by meteorite impacts. The Earth's inner core is solid and spins rapidly, generating a magnetosphere to protect its atmosphere. The moon's entirely solid core produces no magnetic field to prevent the solar wind from blowing away the atmosphere.

Moon Topography

• The most conspicuous topographical feature of the moon is its heavily cratered surface. With no atmosphere to slow down meteorite impacts and no erosion to erase the craters, the entire moon is covered with bowl-shaped cavities. Many of the craters have upraised centers and rims with secondary craters. The largest craters are surrounded by rays of ejected material. Much of the moon is covered by dark regions called maria. These lava-filled basins are the result of giant meteorite strikes.

Earth Features

• The most noticeable feature of the Earth is the deep blue oceans covering 71 percent of its surface. Over 92 percent of the planet's water is contained in the oceans. Some of the Earth's water is frozen into glaciers and ice caps at the poles. Much of the Earth's topography was formed by ancient glaciers. The thick layers of ice created fertile topsoil and gouged out features such as the Great Lakes. Volcanoes and mountains on the Earth are caused by continental drift, as the crustal plates collide and flow over and under one another.