[AZ-Observing] Mars This Morning
- From: "Tom Polakis" <polakis@xxxxxxx>
- To: AZ-Observing@xxxxxxxxxxxxx
- Date: Tue, 29 Jul 2003 09:20:43 -0600
Most of this morning the northern third and southern quarter of Arizona
was cloudy, but Phoenix experienced a clear sky from horizon to horizon.
The dewpoint was 62F with corresponding bad transparency, but the seeing
permitted a magnification of 350x on the red planet.
The central meridian at 2:30 a.m. these days is about 15 degrees. This
puts Sinus Sabaeus toward the gibbous limb, and Mare Erytrhraeum near the
center. I have to admit that albedo features on Mars do not excite me as
much as dynamic features such as those on Jupiter. I am learning that
Mars is dynamic, though. There were no obvious clouds apparent, but the
usual haze on the "non-gibbous" limb showed up brightly. The South Polar
Cap has been interesting to follow since April. It has shrunk noticeably
since my last time out (yikes, over a month). An coordinate grid overlay
sequence posted on the 'marsobserver' group shows it shrinking from a
latitude of 60 degrees south to greater than 70 degrees south during that
period.
One part of the cap has extremely high albedo, appearing overexposed even
to the visual observer. Near the gibbous limb is a small gray notch in
the cap. This feature is saturated on every image of Mars that gets
posted. Speaking of images, the visual view was a refreshing change from
a month of virtual viewing of terrific images by Grafton, Parker, Peach,
et al. While all of those images show striking detail, none of them
begin to convey the experience of actually looking at Mars through the
eyepiece. Again, visual observing rules.
Tom
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