by David Kingsley
It's wet and foggy out there, and skies have mostly clouded over at Stanford after a brief clear spell around 4 or 5 pm.
However, seeing was actually very steady when I first looked through the scope around 6:50 pm. The moon was varying in brightness as thin and thick spots in the clouds would pass by. During the brighter moments, I had a very interesting view of the Ptolemaeus shading effect that Jim Van Nuland mentioned a week ago (see his post below). I could definitely see the several subtle brushes of light extending from east to west across the crater. It reminded me of a beautiful set of light rays I also caught gradually widening across Plato on a particular night last June (/reports/2003.06.07.3.html). The Ptolemaeus shading effect should be going on right now so take a look if you have a scope set up and your skies are better than mine are near Palo Alto..
Jim, I would be interested in your predictions of when to look for the Ptolemaeus brushes again in 2004. Could you also predict when the illumination be the same again to reproduce three parallel rays of light across Plato observed around 9:45 PDT on June 7th, 2003??? I should definitely learn how to do these calculations so I can run other predictions. I would not have set up tonight and seen this effect if I hadn't read Jim's earlier prediction.