“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. Field trip requests are welcome. NOTE: field trip request form for 2022-23 is now live. The spring 2023 schedule of free shows is available here. Images created with Stellarium.
Let’s wrap up our tour of bright winter stars. So far, we have traced out the loop seen in this image from Rigel clockwise through Castor. This circuit of stars is known among sky-gazers as the “Winter Hexagon” or “Winter Oval,” and next up for us is Capella, a bright yellow star currently almost overhead in the evening sky. About 200,000 years ago, it would have been the brightest star in the sky. Capella is in fact, a star system made up of four stars lying 43 light years away. The final star in the oval is Aldebaran, the eye of Taurus the Bull. Aldebaran is cast among a bright V of stars called the Hyades. Binoculars will reveal even more members of this star cluster, which lies 150 light-years away. Aldebaran, however, is not a true member of that star cluster as we now know it is much closer to us at about 65 light-years’ distance.
The planet Mars, along the line between Capella and Aldebaran, is only a guest in the hexagon this winter. Like all the other planets, it moves against the background of the distant stars.
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.