March 29, 2020
Originally published October 16, 2010
south up image by Wes Higgins
I have always been fascinated by Alpetragius because it is such a weird crater. The round mound of a central peak is surrounded by nearly smooth walls, creating what Gerard Kuiper likened to an egg in a nest, and Ewen Whitaker quipped that if it is an egg, its an ostrich egg. It is odd that the rim crest is quite sharp and the wall slumps are so continuous all around the rim. Wes' image captures the smoothed top of the slump masses, and a small nose-like bump on the side of the peak. Our depictions of the crater have greatly improved over the last 50 years but the reason for its unusual interior remains enigmatic.
09-30-10. 5:26 CDT (10:26 UT). 18 Inch Reflector + 4x Powermate + 680nm IR pass filter + Infinity 2-1M + Avistack, Registax V5, ImagesPlus, Photoshop CS4.
Rükl plate 55
Wes' spectacular full mosaic that this was snipped from.