I have never got used to the Greek letters that are used to denote the stars in a constellation. The Plough labels from Alpha at the top of this picture and the circled star is therefore Zeta. However, it isn't actually one star. Looking through binoculars, it is actually two. It is not a binary because they are some distance apart but on the same line of sight. The brightest star is called Mizar and is magnitude 2, which means it is pretty bright to the naked eye. It turns out Mizar is more complicated than it looks. Mizar itself was the first to be found to be a binary system when telescopes were invented. That is two stars orbiting each other. Then later each of those two stars was found to be a binary, so what looks to my eye to be one star is actually four! Now I can pick out a fainter second star next to Mizar. That is not linked to the system and is called Alcor. Alcor itself is a binary as well. So there are 6 stars when it looks like one! See here.
