Equipment: 6? reflector; Pentax 21mm & 7mm ep?s; Moon filter; Ruckl?s Atlas of the Moon
After the rain-forest-like weather we?ve had, lately, it was nice to have a clear and comfortable night to observe. We opened the GEM ?n I Dobservatory at 9:30pm and went straight to the (10 day) Moon.
Though its transit altitude was only 19°, seeing was steady enough that atmospheric turbulance would only be a mild disturbance at high power. Bright enough at low power to merit a Moon filter we spent most of our time around the northern terminator region of Sinus Iridum. The rugged semi-circular ridge that borders the sinus (bay) both starts and finishes with a promontorium (cape). In our inverted view, the lower Promontorium Laplace anchored a well-defined shadow peak.
Just outside of the bay were the two craters named for Helicon, a 4th century BC Greek astronomer, and La Verrier, the mathematician who first calculated the position of Neptune.
Moving ?up? and to the ?right?, we followed a dorsum (wrinkle ridge) to the crater named for Caroline Herschel.
As we let the Moon drift throught the eyepiece we soon came upon an interesting triangle formation, measuring about 25km across, casting three long, narrow, shadows. It took a lot of flipping through pages in Ruckl?s atlas before I identified it as an unnamed formation lying between Delisle Crater and Dorsum Bucher (page 9). An Internet search only turned up the following entry from a Peter Grego:
“The large triangular assembly of mountains in the north is unnamed on Rukl’s lunar map. The mountain group, probably a remnant of the original Imbrium ramparts that were buried by lava flows, occupy an area equivalent to the Isle of Wight. Here they cast spire-like shadows onto the plain”.
With the Moon now dropping behind a tree, we ended our tour with a look at Montes Teneriffe (Teneriffe mountains) and Mons Pico which is 2400 metres high but placed far enough from the terminator, this night, that very little shadow was detected.
The last observation of the night was a very fast-moving meteor coming from the general direction of ? dare I say ? Perseus.
