2011 11 07 – Aristarchus, Herodotus, Vallis Schroteri
2011 11 07, 2315UT – 2011 11 08, 0115UT Aristarchus, Herodotus, Vallis Schroteri
PCW Memorial Observatory, OH, USA, Erika Rix
Aristarchus: Very bright complex crater with steep walls and a small central mountain from Copernician geological period (from –1.1 billion years to present)
Lat: 23.7 deg N, Long: 47.4 deg W
Herodotus: crater with flooded floor, steep slopes to the South and East, from upper Imbrian geological period (from –3.8 billion years to –3.2 billion years)
Lat: 23.2 deg N, Long: 49.7 deg W
Vallis Schroteri: rille from upper Imbrian geological period (from –3.8 billion years to –3.2 billion years)
Lat: 26.0 deg N, Long: 51.0 deg W
Celestron 102mm (1000 fl), 24-8mm Baader Planetarium Mark III Hyperion, 125x, no filter
Temp12.9C, 64% humidity, S: Antoniadi III increasing to I at 125x, T: 5/6
Eyepiece sketch using black Strathmore Artagain paper, Conte crayon and pastel pencil, charcoal pencil
Phase: 31.2 deg, Lunation: 12.14, Illumination: 92.8%
Lib. Lat: -05:06, Lib. Long: +01:36
Az: +163:55, Alt: +17:58
Vallis Schroteri is always a treat to view and the phase was prime tonight. Vallis Schroteri is the largest sinus valley on the moon, 160km long and 1000m maximum depths. The volcanic crater known as the “Cobra” head is near 10km and the body narrows to 500m. It was most likely the source of the sinuous rille Vallis Schroteri that was believed to be formed by rapidly flowing lava.
Aristarchus was very bright and had faint terraces to the western slope. Rays from this crater and Copernicus (and I believe Kepler), as well as scattered craterlets and dorsa, broke up the vast maria surrounding this area. As if the rille isn’t interesting enough, the ray system, domes, mons, Aristarchus plateau, and Montes Agricola add so much more to the view that any one feature deserves an in-depth study on its own. Tonight, however, I was more interested in the overall view, especially with the terminator spilling into the northeastern maria between Ramen and Montes Agricola, making the maria appear as an elongated crater that has opened up on the NW rim, filled up with lava. I also wanted to concentrate on the ray system with the peppering of craters between them.
Looking at past sessions, I stumbled across a sketch I did of this area in April 2005 using the 10” LX200 classic and an 8mm TV Plossl. It’s amazing what experience can offer to the table over the equipment used if you compare tonight’s observation sketch using modest equipment over that in 2005.
2005 observation sketch of Aristarchus
For more reading, please refer to Chuck Wood’s The Modern Moon: a Personal View, pages 165-169. Also, Rukl map 18 and pg 199 (Fifty Views of the Moon).
PCW Memorial Observatory - Erika Rix 