August 16, 2013
A Linear Barrage
image by Avani Soares, Brazil
Imagine being shot at by a machine gun blasting out bullets 1-2 km in diameter - I don't know what calibre that would be. That is roughly what happened to this area northeast of Janssen crater about 4 b.y. ago. The formation of the Nectaris Basin excavated a deep hole and the the removed rocks were thrown out as powder, boulders and small mountains. Some of the mountains may have come apart during their short flight, dropping a series of 1-2 km chunks along the way. Or perhaps a mass of pre-existing material was already fractured and was ejected as a stream of previously adjacent pieces of crust. In either case a series of small mountains fell out of the sky, creating the overlapping craters of the Rheita Valley. Avani's low-light image wonderfully captures four or five members of the basin secondary chain between the craters Rheita (71 km, upper right) and Young (51 km, center right). Rheita partly overlaps the lead crater in the chain, which is more degraded than the others, and also has a rounded front that always makes it look snake-like.
GSO 12" f/5 + QHY 5L colour + Filtro L Astronomik; empilhamento de 195 frames usando AS!2 com pós-processamento no Photofiltre.
21st Century Atlas chart 6.
Yesterday's LPOD: Younger? Older?
Tomorrow's LPOD: An Elusive Globe