06/13/11 – Ephemeris – The lunar crater Aristarchus

Monday, June 13th.  Today the sun will be up for 15 hours and 31 minutes, setting at 9:28.   The moon, 2 days before full, will set at 4:39 tomorrow morning.  Tomorrow the sun will rise at 5:56.

The moon tonight is bright.  The sunrise line or terminator on the moon is crossing the large gray plain called Oceanus Procellarum, the largest of the moon’s seas.  These seas were figments of the first telescopic observers imagination.  They are really huge impact basins into which interior lava flowed.  On the upper left edge of the moon near the terminator is a bright spot on the moon visible in binoculars.  In a telescope it is a crater called Aristarchus.  It is a fairly new crater, probably less than a billion years old.  As a rule the brighter the crater the newer it is.  Aristarchus is the brightest spot on the moon.  Over the years visual astronomers have seen hazes and bright spots from time to time in and near Aristarchus.

* Times are for the Traverse City/Interlochen area of Michigan.  They may be different for your location.

Addendum

The moon with Aristarchus. Created with Virtual Moon Atlas.