“The Sky This Week” appears every Tuesday. It is written by Ian Clarke, Director of the Hatter Planetarium at Gettysburg College. The planetarium offers regular educational presentations about the stars and the skies; there’s something for early elementary through adults. Public shows have concluded for the academic year, but we are still accepting field trip requests for the summer!
This week the moon is out of the evening sky, rising near midnight on Tuesday and later each night after. It’s currently a waning gibbous and will reach last quarter on June 10. In the evening sky after sunset, Venus still dominates the west, with fainter Mars just above and to its left.
Have you seen the Summer Triangle yet this year? Now is a good time. It will be entirely up in the east after about 10:00 PM (see illustration). This asterism, or “unofficial constellation,” is made up of the three bright stars Vega, Deneb, and Altair. Though fairly similar in brightness, astronomers have concluded that they are at very different distances. Vega and Altair are 25 and 17 lightyears away from us, respectively. That makes them relative neighbors of the sun. Deneb, on the other hand, is one of the most distant individual stars you can see with your unaided eye. The most commonly accepted distance is 2,600 light years. That’s very far away but still well within the limits of our Milky Way Galaxy.
Ian Clarke is the director of the Hatter Planetarium at Gettysburg College. In addition he has taught introductory astronomy labs and first-year writing there for over 30 years (not necessarily all at the same time). He was educated at Biglerville High School, the University of Virginia, and the University of Iowa. He lives in Gettysburg.