Tuesday, April 16, 2013
Spiral and Loop
Today's Astronomy Picture of the Day shows Messier 81, a beautiful spiral seen partway between edge on and face on. M81 is found in Ursa Major, and, as such, can be seen easily just about any (clear) night. M81 is also known for the arc known as Arp's Loop, first thought to be a gravitational tail from interactions with M81's neighbor, M82. M81 is best observed actually at lower, rather than higher, powers due to its large size in the sky (about the size of our own full Moon). Large aperture, dark skies, and a low power eyepiece with a wide field of view is your best bet here.