Full moon for May

Here at long last is last month’s shot of the near full moon. Time, weather, and energy permitting, I’m still committed to posting at least one shot of each month’s full moon in 2010.

Depending on your browser, you can either click on the image, or mouse over the area to the right of the image, in order to see the caption/description. (In my browser, Safari for Mac, clicking on the image brings up a new window with a “full size” version. Full size in quotes, because I reduced it to 1200 pixels wide just to make it easy to upload.) I’m not sure why my photo gallery tool behaves this way, but there you have it. If you’re curious about the caption and can’t find it with your mouse, here it is:

Just past full moon, May 29, 2010. 2:18 a.m. EDT. Moon age 15d, 5h, 12m.

This shot was taken a little over a day after the full moon (which was on May 27 at 2307 UT), but it still looks pretty full. The moon was at about 4 degrees eastern libration, and a little over 3 north. That is, the northern and eastern limbs were tilted very slightly toward us. You can tell the moon was past full, because the upper right corner of the moon is starting to show some shadow.

Interestingly, the shadow is much more prominent in that upper right corner; it seems to peter out shortly after you pass the equator heading south. I’ve not quite figured out the geometry of that, but it’s a fun puzzle. Some of the effect might be due to an optical illusion; the Mare Humboldtianum is in that NE corner, and the shadow from its far wall might be deepening the shadows in that area, while the southern limb, lacking this large uniform feature, isn’t thrown into such high shadow.

Anyone else out there have a better idea?