Saturday, June 11, 2011
Alphonsus and Alpetragius
The floor of Alphonsus, of course, has these interesting pits with three zones of surrounding dark material. These are recognized as volcanic pits with surrounding ash. There are at least two such pits in the west, two in the north east and one in the south east. Are such pits found in other craters? The N-S ridge running through the center of the crater has been interpreted as debris (ejecta) thrown out by the formation of Mare Imbrium to the north. Such debris may also have caused the streaks through the south east of Alphonsus, through it rim and just outside the crater.
And then there is smaller Alpetragius (close in to the lower left, south west of Alphonsus) with it's outsized central peak. What is the story here?