The Moon Guide
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U. S. N. O.
The phase of the Moon right now

Schools' Moonwatch 2010

Plato Credit Peter Grego
14 November 2010 The terminator of the 8½-day-old Moon slices through three weather-related seas – Mare Imbrium ( Sea of Rains), Sinus Aestuum (Bay of Billows) and Mare Nubium (Sea of Clouds). The large dark-floored crater Plato (104 km) to the north of Mare Imbrium is on the terminator, as is Eratosthenes (60 km) on the mare’s southern border at the western tip of the magnificent Montes Apenninus (lunar Apennines). Shadows can be seen receding eastward across Plato’s smooth dark floor almost in real time.
Apennines Credit Peter Grego
Apennines and Hadley Rille

On the southern side of Mare Imbrium, Eratosthenes boasts impressive outer walls and secondary impact sculpting which shows up well at such a low illumination.

The magnificent Ptolemaeus (158 km)–Alphonsus (121 km)–Arzachel (100 km) chain dominates the southern central region of the Moon. To the southwest of Arzachel, a broad black line may be seen in eastern Mare Nubium; this is Rupes Recta (the Straight Wall), a 114-km-long cliff formed by faulting.

Tycho (88 km) and Clavius (231 km) in the Moon’s southern highlands are emerging from the terminator. Tycho, a somewhat younger impact crater, shows its large central peak protruding from the black internal shadow. Due south from Tycho, half way to the southern limb, lies Clavius, a vast crater

Ptolemaeus and Alphonsus Credit Peter Grego
Ptolemaeus and Alphonsus
whose floor contains a wonderful arc of craters of diminishing size.

Notes by Peter Grego

Rupes Recta
Rupes Recta (Straight Wall)
Reference map1 Plato; 2 Mare Imbrium; 3 Eratosthenes; 4 Sinus Aestuum; 5 Ptolemaeus; 6 Mare Nubium; 7 Arzachel; 8 Rupes Recta. For a larger map go to

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Mare Crisium
Mare Crisium

MoonWatch evenings

10–11 November 2010

12 November 2010

13 November 2010

14 November 2010

15 November 2010

16 November 2010

17 November 2010

18 November 2010

Jupiter Watch 2010
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