This time I’m going from trios to duos.
One of the more unique and rare features of volcanic origin are concentric craters. These are essentially impact craters that had some magma intrusion push up but not penetrate the crater floor and flood the crater. Interestingly all of these concentric craters all exist along the edge of Mare, and also 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,
Alex.
EDIT: I had it wrong the origin of these structures. I did a bit more reading. See here:
http://www.psrd.hawaii.edu/Aug16/Lun...c-craters.html
You will find a list of these concentric craters here:
http://www.psrd.hawaii.edu/Aug16/Lun...c-craters.html