The Sun Solar System: the Moon Planets observing logs

August 8th, 2003; Lunar observing log

Last night (august 8th 2003) I went out into to field together with a handful of other “lunatics” from our local astronomy club. In summer, the nearly full moon stays very low in the sky. It follows the same path across the sky as the sun does in the winter. As we all live in an urban or suburban environment it is hard to get a good view of the moon from our backyards during this time of year. There are too many buildings, trees and fences that block the view. Around 08.00hr UT we arrived at our observing location and we immediately noticed that the moon looked yellow-brownish, due to the polluted atmosphere we had to look through. It had been warm weather for weeks, and especially the last week was hot, with temperatures as high as 37 degrees Celsius. There had been virtually no wind the last few days, so all the dust and dirt in the atmosphere seemed to cover the earth with a blanket of smog. Apart from that, you could notice that the moon does not shine as bright as in wintertime, when the (nearly) full moon is much higher in the sky. However, since we where there, we decided to give it a try, and build up our equipment.
I used my 8 inch TAL 200K, with a 32mm Televue plossl and a 25, 20, 15, 12 and 10mm Vixen Lanthanum. I also used my TAL Barlow. There were no filters used.

I started of at Mons Gruithuisen Gamma, Mons Gruithuisen Delta and the 16-kilometer wide crater Gruithuisen. (Rukl 9, Hatfield 6 g2/g3). These features form a triangle with in the middle another mountain-like feature that does not have a name in the Rukl Atlas of the Moon. To the east of this unnamed mountain, a 50 km long ridge-like feature with a small crater (H) near the southern end could be seen. When near the terminator, Gruithuisen Gamma, Delta and the unnamed mountain to the south cast quite some shadow across the lunar surface, a beautiful sight. I could not detect the small craterlet on top of Mons Gruithuisen Gamma.
The three Gruithuisen features are named after Franz von Paula Gruithuisen, a German (Bavaria) physician who was appointed professor of astronomy at Munich in 1826. According to one of my fellow observers, Gruithuisen thought he could see a city on the moon, with big structures and broad streets. If you want to observe this “city” yourself, look far a feature that looks like a fishbone, located about halfway between the craters of Mösting and Erathosthenes.

At 21.00hrs UT I went to the southern part of the moon, where the sun lighted the western rim of Schiller (Rukl 71, Hatfield 10 g4, 12 c4). Schiller is a very elongated crater of 179 km long and 71 km wide. Due to its form it can be identified very easily. Behind the western, sunlit ridge of Schiller, another small ridge seamed to appear. Right beside Schiller, on the eastern rim I could see Bayer, named after Johann Bayer, the author of the famous star atlas “Uranometria”, published 400 years ago, in 1603. From Schiller I went to Gassendi (Rukl 52, Hatfield 9 h5, 11 c4). In Gassendi, the two big central peaks could be readily seen. I could not detect any of the Rimae Gassendi this time. Gassendi A and B were very easy to detect, and on the southern edge of mare Humorum, Doppelmayer was visible. The Rimae Doppelmayer stayed invisible.

Around 22.00hrs UT I swept across the lunar disk to the east, to Mare Crisium. There I found, between Mare Crisium and Mare Tranquilitatis, Palus Somni or the marsh of sleep (Rukl 26, Hatfield 3 d4). This big diamond-shaped feature is even visible with small binoculars. On the eastern edge of Palus Somni lies Proclus, a crater with a sharp edge. Tonight it looked like a bright ring of light, standing out from it surroundings. In fact on this night it was one of the brightest features I could detect on the lunar surface. Some beautiful rays spread from Proclus in different directions, but tonight they are not so prominent.

Thanks to Ton Baten, one of the biggest “lunatics” in our group (and probably worldwide) I got something special to end my observing session, a feature I had never noticed before. To the east of Mare Crisium he detected an elongated dark feature. After looking into our different moon atlases we agreed that it had to be Mare Marginis (Rukl 27, Hatfield 3 a4), which lies on the very edge of the lunar nearside. The elongated dark feature was so big that it could not possibly be anything else. Also its position seemed to be correct. So this heavily air-polluted observing session had a fruitful end. At 01.00hrs UT on Saturday morning I drove home with a “new” discovery logged into my lunar observing book.

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