See The Most Famous Double Star In The Sky


Find Mizar and its companion Alcor in the bend of the Dipper’s Handle

Clear skies are forecast for the region tonight so why not try to spot something new in a familiar group of stars. Focus your attention on the Big Dipper, high in the northeastern sky as soon as night falls. If you study the chart above, you’ll see that the Dipper is part of the much larger constellation Ursa Major, the Great Bear.

Now take a look at the bend in the Handle. How many stars do you see? If you have reasonably good vision, you should be able to resolve two. The brighter one is Mizar, the dimmer, Alcor. One of their nicknames is the Horse and Rider, which I like very much.

The pair is about 80 light years away, and despite much study, scientists still aren’t certain if they’re physically related. If you have a small telescope, you can split Mizar again and see its small, bright companion. These two are physically connected. The smaller one revolves around Mizar just the way the Earth revolves around the sun.

Using larger telescopes and an instrument called a spectroscope, astronomers have found that Mizar and its telescopic companion are each doubles in themselves. That would make Mizar a quintuple star.

Double and multiple stars are very common in our galaxy. So much so that the sun stands out a bit of a loner in the grand scheme of things. While we’ll probably never see the five daily sunrises and sunsets like the citizens around a Mizarian planet, we’re grateful for our singular sun just the same.