Saturday, September 10, 2011

Batty Moon!

While our friends were visiting last weekend, I awaited their return from shopping near their hotel, which just happened to be across the street from where we occasionally go watch the bats come out at sunset (Campbell Ave bridge across the Rillito).  With them still away, I stood about 50 yards west of the bridge and took a few shots of the stream of bats passing near the quarter moon in the southern sky.  This was the best of about a dozen frames I took before it got too dark to see them silhouetted against the twilight.  With a shorter exposure to properly shoot the moon, the bats would have been invisible... 

Today, looking at the exposures more critically, I noticed a bright spot just above the moon - a star that was scheduled to be occulted, or blocked by the moon, if viewed from the correct location.  As described on the Sky and Telescope website, the star is Delta Scorpii (4th brightest star in the constellation Scorpius).  The chart in the link there shows were we're just north of the "Northern Limit", so no occultation was visible from this location, but from the southeastern US, the star did disappear behind the disk of the moon.  I've seen many such occultations of stars and planets, in fact, with a reasonably sized telescope and a crescent moon, one can watch random faint stars disappear behind the earthlit "dark side" of the moon most any night as it slowly moves around the earth in it's orbit.

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