Copernicus Crater
This image was originally taken as part of a series of spacecraft missions sent to the Moon in the 1960s to characterize possible landing sites prior to the actual moon landings. The crater is 93 kilometers across and is one of the younger large craters on the Moon, thought to have formed within the last billion years. It can be seen with binoculars, on the western portion of the hemisphere that faces the Earth, just south of the large dark feature known as Mare Imbrium.
Unlike many other large craters on the Moon, its floor has not been covered by lava, allowing you to see the features associated with the impact itself including the central peak or central mound. When a large crater forms, it starts off as a gigantic explosion and a huge, unstable hole in the ground. There is so much energy associated with forming a large crater that after the blast, material actually flows or rushes back in to fill the temporary gap. That material flows in from all sides and comes together at the center of the crater, causing the material to pile up and creating a central peak.
This process defines a “Complex crater”, one that is more complicated than a simple crater that is just a hole in the ground. How big a crater needs to be to be complex versus simple depends on the energy of the impact, and so it also depends on the gravity of the object; on the moon, craters larger than about 20 kilometers in diameter are usually complex craters.
In 1966, Time Magazine ran a quote by a NASA scientist describing this shot as “one of the great pictures of the century.”
-JBB
Image source: https://apod.nasa.gov/apod/ap070616.html
Reference:
http://content.time.com/time/magazine/article/0,9171,898477,00.html
https://www.nasa.gov/mission_pages/LRO/multimedia/lroimages/lroc-20100728-burgcrater.html
