Crater

Definition

A crater is a circular depression on a planetary surface typically formed by the impact of a meteorite. Craters can also result from volcanic activity or explosions but are most commonly associated with impacts in an astronomical context.

5 Must Know Facts For Your Next Test

1. Impact craters are characterized by their raised rims and sometimes have central peaks formed by the rebound of the planet's crust.
2. The size and morphology of an impact crater depend on the size, speed, and angle of the impacting body as well as the geological characteristics of the surface.
3. Crater counting is used to estimate the ages of planetary surfaces; more craters generally indicate an older surface.
4. Lunar highlands have significantly more craters compared to maria, indicating that they are older regions of the Moon's surface.
5. Ejecta blankets, which are layers of debris surrounding craters, provide clues about subsurface materials and the history of impacts.

Review Questions

• What are the primary characteristics that define an impact crater?
• How does crater counting help in determining the age of a planetary surface?
• What is an ejecta blanket and what information can it provide?

Related terms

Ejecta Blanket: Material that is ejected from an impact crater and deposited around it.

Central Peak: A peak that forms in the center of a larger impact crater due to rebounding crust.

Lunar Highlands: Older, heavily cratered regions on the Moon compared to younger, smoother maria.