Wednesday, April 11, 2007

20070411 - Trying for Mare Orientale

Session name: 20070411.0345

snipped image of M. Orientale I woke to an alarm at 3AM and readied to go to Carl Schurz Park. I awoke The Wife and she mumbled how noisy I was. A short while later I arrived at the eastern horizon-friendly observatory on John Finley Walk where Moon had already risen. As I set up the scope I could hear more than the sound of silence. First to my ears were some waking robins, becoming a chorus when I started to pack after 5:30AM. A very low frequency rumbling from tires on the highway below me kept a cadence that I didn't count. My eyes wandered from the glass topped river - calm. And then I looked up beyond Moon & Jupiter.

Summer is nearly here. In terms of right ascension, we're only a few hours away. The Summer Triangle had risen entirely, Jupiter appeared to be in Ophiuchus, or may have been in that tiny area of sky on the ecliptic that belongs to Scorpio. Sagittarius was low in the southeastern sky, not yielding a hint that the heart of our Milky Galaxy lies within its borders. More northerly and much higher Vega held Lyra above any treetops. My first look at the whole summer sky this year.

It was Moon and western libration that brought me out this early. Typically, I don't observe a waning Moon since it rises at this wee hour and I'm in bed until it becomes the old crescent Moon which is within a day of New Moon. Today, it is the promise of seeing Mare Orientale. It has been a very elusive feature and favorable librations with an appropriate phase seem to be rare. I don't think we've had one in a long, long while.

When I turned the scope on the lunar disk, seeing was noticeably poor along the limb. I shot a bunch of photos and none were worthy. I could see the lava colored floors of Lacus Veris (Lakes of Spring) and Lacus Autumni (Lakes of Autumn), on the outskirts of Orientale basin. But I couldn't say I saw Mare Orientale or Montes Rook. I noted their locations and irregular shapes. Nearby great Grimaldi, a crater with a similar lava-colored floor, served as a landmark to return that part of the limb. As noted earlier, observing along the limb was like looking through unsettled water.

image credit: snipped screen grabbed from USGS Moon General Image Viewer