Solid solar system bodies—rocky planets, moons, and asteroids—are shaped by a long history of geological processes. Mountains, canyons, craters, and other topographic features develop over time as various processes alter the terrain. The surface features of planets and moons act as a record, providing information about their origin and evolution.

Here are the big ideas you will learn about in this lesson:

• Geological processes such as impact cratering, volcanism, and erosion alter the surfaces of Earth and other objects in the solar system.
• The principle of uniformitarianism states that natural processes that operate on Earth also operate throughout the universe and are unchanging over time.
• Scientists can apply knowledge about Earth to study and interpret observations of other worlds.