Starting from the top, 81 km Pre-Nectarian ring plain Eddington is is merely a remnant of a once large, complex crater. Having formed from an impact only a few hundred million years after the Moon was formed some 4.5 billion years ago, it may have kept it's rugged walls, glacis and central peaks for nearly a billion years before the glowing basalt floods of Oceanus Procellarum cascaded over it's rim, inundating it's floor and nearly filling it to the brim. To the east Eratosthenian aged, 44 km Seleucus, displays youthfulness in it's fresh looking walls and terraces. Further down the terminator, Upper Imbrium Krafft and Cardanus appear to be a perfect pair, at 53 and 51 km respectively, and besides their near identical appearance, they also share a rille-like structure that lunar orbiters have identified to be a catena, a linear alignment of overlapping craters. It is still uncertain where these secondaries originated. At the bottom of the triptych, and formed only a few hundred millions of years after the Eddington impact, lies the degraded walls of 77 km Nectarian Olbers. It's somber lava plain is covered in deep shadow. To the east, enigmatic Gamma Reiner, a surficial stain on Oceanus Procellarum, is associated with a strong magnetic anomaly. It has been proposed that it represents the remains of a comet collision, or possibly the results of an antipodal impact.
Subject: Eddington to Olbers Rukl: 17, 28
Time: 10:30pm - 1:30 PDT Date: May 7-8, 2009
Seeing: Antoniadi II-III Weather: clear
Lunation: 13.01 days
Colongitude: 73.2 deg.
Lib. in Lat.: +06 deg. 57 min.
Lib. in Long.: +05 deg. 27 min.
Phase: 11.1 deg.
Telescope: 12" Meade SCT f/10
Binoviewer: Denkmeier BV-25 with 2X nosepiece
45 deg. W.O. erect image diagonal
Eyepieces: 26mm Meade Super Plossls
Medium:Sketch White and black Conte' on Black 400 Strathmore Artagain paper
Sketch size: Triptych composed of three 9x12 sheets of paper