Sunday, December 04, 2005

20051203 - The Sun and Crescents

Session Name: 20051203.0953

Set up at the Rock, a location at the south end of Central Park nearby Wollman Rink. The ice skating rink is partially visible through the trees.

It was a laborious session to say the least. The clouds kept coming in large, dark tufts from behind the buildings looking manhattan-south. The taller buildings rise about 23° in altitude so at times it looked as if the quick, moving clouds would yield large clear, blue sky but that wouldn't be the case. Seeing was poor and it was diffcult to use magnifications as much as 97x. I observed mostly at 63x and still had to wait for turbulence to settle. When showing Sol to the passersby, around 10 persons, I lowered it to 41x for a sharper image.

Earlier in the morning around 8:30, I held up the Baader film to Sun to see a large dark line in the center of the disk. Sun was rising into the CitiCorp building so when the building occulted the solar disk, I could see that the line was to the preceding side. Later during the observing session I had a difficut time seeing group 826 through the vieiwing window.

I continue to practice sketching. This session's sketch is below. For me, group 826 was very difficult to draw. The detail was amazing during steady moments, particularly the penumbra surrounding the following two spots of that group. Actually, the sketch shows those two spots and penumbra "larger than life". The area covered was smaller, and I estimate the length of the group relative to the separation of spot "A" to "C" to be between 1/3 and 1/2.

I finished up the session, observing Venus. I observed Venus in handheld 7x50 binoculars to confirm that the crescent shape can be discerned. I feel it is pretty easy to see when the bins are held firmly. Around the globe, Ian had recently wrote about this from Australia. While one is there, check out his image that displays Venutian changes in size and phase.

I was unable to observe Moon from where I was. The highest point it would reach would be 20°, and from the photo above one can see that there are windows of opportunity where the buildings are low. Today, the clouds were bad, obstructing the sky along this horizon. It wasn't until I arrived home and looked out our living room window, due manhattan-South, that I was able to see Moon. There was a 6.0% illuminated crescent about to set into the Rhiga Royal hotel.

At this time, both Venus and Moon are interior to our orbit around Sun and seen in the sky to the east of Sun. As a result, their crescents are illuminated on the same side. There is a difference, however, which of their phases they each approach. Moon, having passed New Moon phase, is waxing to First Quarter. Venus is waning to "New Venus" phase, where it will lie between Earth & Sun, after having passed greatest eastern elongation that had exhibited a last quarter. Check here for a more complete description of Venus phases; and, here for a desc ription of lunar phases.