Raising Eyebrows on the Floor of Imbrium

Aristillus and Autolycus
Sketch and Details by Richard Handy

Sitting replendently on the the eastern margin of Mare Imbrium, 56 km Aristillus and 41 km Autolycus, brothers of Copernician age, are a startling sight in the late lunar afternoon sunshine. Hexagonal in appearance, Aristillus’s broad and radially splayed glacis dominates the mare surface in this region. It’s wide, brilliantly lit terraces apparently have evidenced some mass wasting since its creation a little over a billion years ago. Resting on the floor, some 3650 m deep, the glowing central peaks are roughly 900 meters high. Rays, some quite prominent, emanate from the crater’s center. To the northwest of Aristillus, swathes of darker mare may indicate areas not fully dusted by the ejecta from this massive impact, or perhaps ejecta excavated from deep within the extant mare is responsible for these low albedo areas. Approximately 60 km to the south, Autolycus’s glacial nimbus appears almost serene in comparison to the complex nature of Aristillus’s glacis. Half of the floor of Autolycus is composed of quite torturous terrane including a strange floor subsidence to the eastern section of the floor.

Here are the sketch details:

Subject: Aristillus and Autolycus Rukl: 12
Date: 10-13-06 Start: 9:15 UT End: 10:50 UT
Lunation: 20.90 days Phase: 277.5 deg Illumination: 56.5%
Colongitude: 164.8 deg Lib. in Lat.: -5 deg 40 min Lib. in Long.: +7 deg 39 min
Seeing: Antoniadi III-IV with 30 seconds of Ant. II every 20 minutes
Weather: Clear early, turning to occasional clouds mid to late during session, 10-15 knot winds late.
Telescope: 12″ Meade SCT F10
Binoviewer: W.O. Bino-P with 1.6X Nosepiece.
Eyepieces: W.O. WA 20mm Plossls
Magnification: 244X
Lunation: 18.48 days Phase: 311.1 deg Illumination: 82.9%
Colongitude: 133.7 deg Lib in Lat.: -3 deg 53 min Lib in Long.: +5 deg 12 min
Sketch medium: White and black Conte’ Crayons on black textured Strathmore paper.
Sketch size: 18″ x 24″