OR October 18, 2007

by Michelle Stone

I first set my sights on Jupiter but it was playing hide and seek behind the clouds. Seeing was fairly good for it being so early in the evening. I did manage to catch a couple of glimpses here and there. It's a bit difficult to make out any real detail with a small scope and with the planet so low towards the horizon but the banding is clear. The darkest of the bands just north of the equator is most prominent. The others were on the edge of detection.

After a quick look at Jupiter, I turned the scope to the SSW to look at... gasp... the moon! I truly have become a heretic after observing deep space objects all these years. But you know, my observing has been very infrequent this past year. I've wanted to get out more but just can't get up the will power or time to set up every night. I've decided to do something at least a couple of times a week. And so yes, gentle readers, that means getting into some lunar observing.

Mare Ibrium.

... is in the shadows this evening. However two of the prominent ranges were prominently visible this evening. The Montes Appenninus were the first that I saw through the telescope. This range has a special memory for me. It was the first lunar range that I took the time to look up... just two weeks ago. I'm sure that it will become one of my favorites. After doing quite a bit of backpacking in the Sierra Nevada granite, I can only imagine just how rugged these hills are. Montes Alpes to the northwestern rim of the mare put on a striking show this evening. As I began my session, they did seem impressive. But as the sun rose by just a couple of hours, the contrast changed just enough to give them a sense of great releif. They became pebbled as popcorn sitting on the smoother lunar surface surrounding them. Valles Alpes, showed prominintly disecting the Alpes from East to west. I wonder what could have created a valley so wide, straight through this rugged mountain range.

Crater Ptolemaeus.

PA shows fairly dark and deep. West and slightly south by one degree is Ptolemaeus M. M is not visible however just south of where it should be by .2 degree is a depression prominently displayed this evening due to the angle of the light. Farther south by .5 degrees is another depression also showing quite nicely. Above M by .5 degree is a double depression. In the scope it looks as one entity at first look but careful consideration shows both members. Ptolemaeus D is north and East by about .5 degrees. In all there is a semicircle of what appears as craterlets about 2/3 the distance from the center of the crater Ptolemaeus. As my observing session drew to a close, these depressions were nearly invisible. I have a hunch that these are visible for only two or three hours each month due to their shallow depth.

When I first looked at these, I was captivated by their circular nature about the center of the crater and for this reason, I became curious as to what they were named. They seemed fairly well defined and similarly sized at 10 to 20 kilometers in diameter. They did not show on the chart I was using so I pulled out my Rukl. There was no indication that there was anything there. So I rechecked my notes and took another view through the scope, carefully taking care to make sure I hadn't made a mistake. There they were, a nice string of 4 dark circles. With some online research, I discovered the LAC charts. These have incredible detail and did indeed verify that what I was seeing was correct. These charts show that these depressions can not be more than 300 feet deep according to the topographical overlays.

I'm not much of a lunar observer, but I just found something that I believe is rarely seen from the earthside. Hooray!

South of Ptolemaeus are the two craters Alphonsus and Arzachel. When I began my observing session the shadows behind their central cones were short. The peaks were bathed in sunlight giving an impressive view. As I wrapped up my session, these shadows had extended to the rims of their respective craters. Alphonsus was especially interesting projecting very thin needle like shadow westerly. That peak must be exceedingly narrow and tall.

I suppose that I should do some reading on lunar observing. I can now see that there is real action on the moon. Nothing is ever static along the terminator. Shadows come and go revealing interesting features. Go figure... I've always hated the moon because it lights up the sky and makes deep space observing nearly impossible. But you know what? It is a new world for me to explore.

Observer: Michelle Stone
Telescope: SV80S
Eyepiece: Takahashi 7.5mm LE with Celestron 2X barlow
Date: October 18, 2007 7:00 PM to 9:30 PM PST
Location: Plettstone