Observation Notes:
This area was the most prominent set of features on the terminator when I checked it out tonight. The flooded basin displayed an arcuate rille sliding along the inside of the rim. The rim threw stark daggers of shadow, while the basin showed a soft transition from shadow to light, nicely demonstrating the moon’s curvature. The most prominent crater in the south end of the basin, Picard, is 23 km wide.
Factoids:
Mare Crisium is a basin, created during the Nectarian epoch, while the mare material is of the Upper Imbrian epoch. Mare Crisium is an elongated crater that is 100 km wider in the E-W direction, although it doesn’t appear that way because it is close to the edge of the moon from our vantage point. Cleomedes Crater is a flat basined crater with a central peak that is 126 km in diameter and 2.7 km deep.
| Subject | Mare Crisium and Cleomedes Crater |
| Classification | Lunar Maria and Crater |
| Position | Northeast |
| Age/Phase | 17 days old |
| Size* | Mare Crisium: (dia. 500 km E-W x 400 km N-S); Cleomedes Crater (dia. 126 km x depth 2.7 km) |
| Date/Time | 10/30/04 – 11:45 PM |
| Observing Loc. | Flagstaff, AZ – Home |
| Instrument | Orion SVP 6LT Reflector (150 mm dia./1200 mm F/L) |
| Eyepieces/Mag. | 10 mm + 2X Barlow (240X) |
| Seeing | 3/10 |
* Based on published data.