What is Impact crater?
[[Image:Tycho crater on the Moon.jpg|thumb|230px|The prominent impact crater Tycho on the [[Moon]]. ''[[NASA]]&nbsp;photo.'']] [[File:Craterstructure.gif|thumb|right|250px|Impact crater structure]] [[File:Antarctica Map Wilkes L Crater.png|thumb|230px|Position of supposed Wilkes Land crater]] [[File:Azuara-impact-structure-Shocked breccia.jpg|thumb|230px|Shocked [[breccia]] from the Azuara impact structure, [[Spain]].]] [[Image:Wells creek shatter cones 2.JPG|thumb|right|230px|Close-up of shatter cones developed in fine grained [[dolomite]] from the Wells Creek crater, [[USA]].]] '''Impact craters''' are [[crater]]s formed by [[meteorite]]s or [[comet]]s striking the [[Earth]] or other solid body. There is a system for recording and assessing craters.<ref>[https://www.unb.ca/passc/ImpactDatabase/CIDiameterSort2.htm Earth Impact Database]</ref> == Largest craters on Earth == The five largest ''confirmed'' impact structures are: #[[Vredefort crater]], [[South Africa]]: 160&nbsp;km diameter, 2023 million years ago.<ref>Revised estimate. [http://www.passc.net/EarthImpactDatabase/New%20website_05-2018/Diametersort.html]</ref> #[[Chicxulub crater]], [[Mexico]]: 150&nbsp;km diameter, 65 million years ago. #[[Sudbury Basin]], [[Ontario]], [[Canada]]: 130&nbsp;km diameter, 1850 million years ago. #[[Popigai crater]], [[Russia]]: 90&nbsp;km diameter, 35.7 million years ago. #[[Acraman crater]], 90&nbsp;km diameter, [[South Australia]], ~590 mya. #[[Manicouagan crater]], [[Quebec]], Canada: 70&nbsp;km diameter, 214 million years ago. There are some other suggested impact structures which are larger. It is a feature of the Earth that [[climate]], [[weather]]ing and [[plate tectonics]] removes most of the older features and events. In comparison, the [[Moon]] retains a nearly complete record of its past impact events. The [[Implication (grammar)|implication]] is that the Earth once suffered a similar bombardment in its early history. This period is known as the [[Late Heavy Bombardment]], because it occurred after the Moon