Tuesday, December 21, 2010

Solstice total lunar eclipse

Last night's total lunar eclipse was the first to occur on the winter solstice for at least several hundred years, making it a very rare event. Since the weather forecast for my area promised at least relatively clear weather, I set up the 10-inch telescope because it had dew heaters and digital setting circles, which my 6-inch is not equipped with. I recently acquired a new dew heater controller called a Dewbuster, a device that pulses the current and also uses a temperature probe to prevent too much heat from interfering with the views due to heat blooms in the telescope. It also conserves battery power, a big plus for long observing sessions when the dew is extremely heavy like it often is here in coastal Alabama. As soon as it began to get dark, I set up the telescope, and turned the dew heaters on.

I was planning to look at Jupiter, Uranus and Neptune before they dropped behind the trees, but the seeing turned out to be horrible and Jupiter was a large, bright squirming blob. The moon looked like I was watching it from the bottom of a swimming pool. I also discovered the digital setting circles were acting in their usual temperamental manner and thin clouds were passing through, so I left the telescope outside and did other things until the eclipse began. It turns out there was a stationary front near my area, and weather fronts create bad seeing and annoying thin clouds. Had it not been for last night's eclipse, the telescope would have stayed inside last night and I would have been reading a book or watching television.

By 12:30 a.m. the moon was entering the umbra or dark inner shadow of the Earth, making it look like a cookie with a bite taken out of it. At last the horrendous turbulence let up somewhat  but the view was still shimmering from time to time. I opted to use a 32mm and a 21mm eyepiece that gave  magnifications of 41X and 63X respectively, until the coma corrector lens started to fog up. After taking it out, I was looking at the moon at 36X and 57X respectively, which is very low power for a 10-inch Dobsonian, but I had a nice view of the increasingly eclipsed moon. At first, the portion that was eclipsed was a dark grayish brown but as the moon passed deeper into the umbra, the moon took on a dark brownish red color. Around the edge of the umbra, the moon took on a bluish gray color. By 1:15 or so the moon was almost entirely in the umbra and by 1:30 it was completely immersed.

During this time the bluish gray color faded and most of the moon took on shades of brownish red. The stars that otherwise are washed out both to the unaided eye and the telescope came out and I looked at the bright star cluster M-35, which was only a few degrees away from the eclipsed moon. I also stopped to look at the sword of Orion, at the heart of which is the great Orion Nebula. As for the moon itself, it took on a three dimensional appearance as it drifted in front of background stars, dozens of which were visible. Normally the full moon is a whitish, glary object that looks flat and two-dimensional to me through any telescope. The huge light gathering power of a 10-inch Dob makes it almost painful for me to look at without a dark gray filter to dim the moon to a comfortable level. I was able to see with ease the moon's orbital motion as the eastern limb approaches then covers up star after star while others pop back into view on the western side.

By this time a most unwelcome visitor appeared for sky watchers like me, clouds. Few in number, they became steadily more numerous as the  eclipse progressed. By 2:00 a.m. the moon was past mid-totality and the eastern limb was beginning to brighten again. The moon made a wonderful sight as it was at the juncture of the constellations Taurus, Gemini and Auriga. The bluish gray color was starting to return as the planet Saturn was finally climbing above the tree line. Then the weather completely went down hill, and the entire sky rapidly clouded and fogged over. By 2:30 it was time to put away the telescope but as I carried the base back into the house I watched the eclipsed moon appear in a break in the clouds. I was most happy to had the opportunity to watch this rare event.

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