One of the more unique and rare features of volcanic origin are concentric craters. These are essentially domes that have collapsed in on themselves due to magma displacement. While there was at first a push up by magma, the pressure was reversed and that material was then pulled down. The result of this is a double ringed concentric structure. Whether or not it was an impact that led to the initial formation of the structure I do not know. But all of these concentric craters all exist along known volcanic areas, namely because they hadn’t been obliterated by the Great Bombardment.
There would appear to be an upper and lower limit to the size of these. The largest concentric crater is only 30km, but most are between 6 to 15km, with a few smaller and a few larger.
Hesiodus A is one of the easiest to find & one of the largest, and Marth is just a little west of it.
The pic was done using a 9” Santel Mak with a 224 colour camera. Seeing conditions were not good on the night. Still working on my processing skills. Processed using Autostakkert and Registax6, and touched up using PhotoDirector.
Thanks for looking,
Edited by maroubra_boy, 28 July 2021 - 08:07 PM.