101 Must-See Cosmic Objects: Mizar and Alcor

For most people living in the Northern Hemisphere, the first double star we notice is Mizar (Zeta [ζ] Ursae Majoris), the middle star in the Big Dipper’s handle. Located just to the northeast is Mizar’s faint cohort, Alcor (80 Ursae Majoris). Mizar shines at magnitude 2.3, while Alcor is magnitude 4. The pair are separated by 11.8′, which is resolvable with the unaided eye if the sky is dark enough and your eyesight is good enough. In ancient times, some cultures even used these