Some people go their own way. And so do some stars. Instead of sticking with the stars around them, they follow their own path around the galaxy.
That’s the case with Dubhe, the star that marks the top right point of the bowl of the Big Dipper. Five of the seven stars that outline the dipper belong to a star cluster — a big stellar family. As a result, they move through the galaxy together. And they’re all about the same distance from Earth — roughly 80 light-years.
The dipper’s two other stars don’t belong to the cluster. Dubhe is the more distant of the two. In fact, it’s the most-distant of all the dipper’s stars — about 125 light-years away.
Dubhe forms its own little family. It consists of two pairs of stars. The leader of one pair is at the end of its “normal” lifetime, so it’s puffed up to giant proportions. It’s especially bright, so it contributes most of the light we see as Dubhe. Its companion is a couple of billion miles away from it, so the two stars orbit each other once every 45 years or so.
The other pair is pretty impressive as well, but a long way from its brighter siblings.
Because Dubhe isn’t related to the dipper’s other stars, it’ll move out of its position in the dipper much sooner than the others. That will stretch the dipper out, eventually pulling it apart.
For now, look for Dubhe in the northeast this evening. Dubhe leads the dipper up into the sky — and high across the north during the night.