Department of Astronomy

May Third is National Astronomy Day!  Take a few minutes to experience the night sky.  It’s an ideal time to enjoy the first quarter moon, which will be up in the evening.  At first quarter, deep shadows accentuate the moon’s mountains and craters, increasing contrast so they are easier to see.  If you have binoculars available, the view is especially striking.  And don’t worry if the weather’s bad.  We celebrate Astronomy Day twice a year, in spring and fall, so you’ll get another chance then.  Actually, you get another chance around every first quarter moon, so no need to wait until fall. 

The moon will be full on May 12 and new moon occurs on May 26.  In its journey across the sky this month, the moon will past near Mars on May 3^rd and Spica on May 10.  Then the action moves to the morning sky in the east, as the moon passes Saturn on May 22, Jupiter on May 26, bright Venus on May 23, and Mars again on May 31. 

Jupiter will still be visible in the evening twilight sky in the west in the early part of the month.  If you can catch a star party, views of Jupiter against the twilight sky offer an opportunity to see its dark bands and bright zones.  Jupiter will be more difficult to see after May 7 as it moves closer to the sun. 

The Eta Aquarii meteor shower continues through most of May, peaking on May 5^th.  The Eta Aquarii meteors are best seen in the early morning toward the east, after the moon sets in the west, and before morning twilight.  These meteors are specks of dust from Halley’s Comet moving through the Earth’s atmosphere at 40 miles per second, or so.  Expect to see about 10 in an hour from a dark site. 

Late May also presents an opportunity to see the only naked eye asteroid, Vesta.  While Vesta is a little smaller than our largest asteroid Ceres, Vesta wins the brightness competition, being both more reflective and a little closer to us.  Vesta is still pretty faint, though, so you’ll need a dark sky and a good sky chart.  It will be a little below the line between Arcturus and Spica.  Binoculars and a dark site will help!