Glossary term: Crater

Description: A crater is a circular depression in the surface of a solid planet, moon, or other small object in space. Some craters are volcanic, especially on Earth and Venus, but most are impact craters, caused by the impact of a large space rock or comet nucleus. There are dozens of impact craters on the surface of Earth, and thousands on the Moon. The maria, the large, darker, circular features on the Moon are giant impact craters, formed billions of years ago, and then filled with lava, which has since solidified.

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The OAE Multilingual Glossary is a project of the IAU Office of Astronomy for Education (OAE) in collaboration with the IAU Office of Astronomy Outreach (OAO). The terms and definitions were chosen, written and reviewed by a collective effort from the OAE, the OAE Centers and Nodes, the OAE National Astronomy Education Coordinators (NAECs) and other volunteers. You can find a full list of credits here. All glossary terms and their definitions are released under a Creative Commons CC BY-4.0 license and should be credited to "IAU OAE".

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The asteroid Ceres, roughly spherical with a grey surface, many craters, some of which reveal white subsurface water ice.


Caption: True-colour image of the asteroid Ceres acquired by the spaceprobe Dawn in May 2015, at a distance of 13641 km. The prominent, bright crater at right is Haulani. The smaller bright spot to its left is exposed on the floor of Oxo. Ejecta from these impacts appears to have exposed bright material, probably water ice.
Credit: NASA / JPL-Caltech / UCLA / MPS / DLR / IDA / Justin Cowart
License: CC-BY-2.0 Creative Comments Attribution 2.0 Generic icons