Alphonsus, middle of the Ptolemaeus Chain

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Photographer:

Ken Vaughan

Location of Photo:

Cattle Point, Victoria, BC, Canada

Date/Time of photo:

22 Jan 21

Equipment:

12" Meade LX200GPS, ZWO ASI178MM, Astronomik 642 filter

Description:

From a lunar geologist's point-of-view, this might be the most interesting of the three craters in the chain. You can see that Alphonsus' floor and rim are streaked and cracked, with the ridges and furrows parallel to the Imbrium Sculpture seen especially vividly to its northwest. Alphonsus is older than Arzachel, looking much more raggedy and worn. You can see four dark-haloed craters inside Alphonsus, probable volcanic vents. Alphonsus doesn't have any large craters on its floor but does have Alphonsus G (4 km) in the north and Alphonsus J (8 km) and Alphonsus A (4 km) in the south. Rima Alphonsus wends its way north to south in the eastern half of the crater. The teardrop-shaped Alphonsus B (24 km) lies to the east of the main crater.