The star that anchors the Big Dipper’s handle is a bit of an outcast. The five stars that make up the dipper’s middle are members of the same family — the Ursa Major Moving Group. They were born from the same cloud of gas and dust, and they move through space together. The stars at the ends are different. Tens of thousands of years from now, they will have moved a good distance from the others as seen from here on Earth, pulling the “dipper” apart. Alkaid is the end of the dipper’s handle. It’s farther away than the members of the moving group — 100 light-years. And it’s only about 10 million years old, which is far younger than the members of the moving group. Ten million years isn’t long on the astronomical time scale — the Sun is four-and-a-half billion years old. Even so, Alkaid is getting well along in life because it’s more than six times as massive as the Sun. The cores of heavy stars are much hotter than those of lighter stars, which revs up their nuclear reactions. They consum
