Grades K–2 · Earth & Space
Why does the Moon have so many round dents?
Many round dents on the Moon are craters. They formed when objects from space struck its surface. A fast collision can throw material out and leave a hollow with a raised rim.
In the diagramA collision can leave a lasting hollowImpactAfterwardrim + hollow + scattered materialEnlarged example snapshots; the Moon has little weathering by air or water.
A crater can be much wider than the object that made it. The moving object carries energy. When it hits, that energy changes the ground and sends broken material outward.
On Earth, rain, rivers and other changes can wear old marks away. The Moon has no rain or flowing rivers like ours. Many of its craters therefore keep clues about collisions from long ago.
About this explanation
Starting knowledge: Recognize the Moon and understand that a collision can change a surface.
Sources
- NASA — Moon Craters