Moon and Antares

Stars are big — really big. The Sun, for example, is more than a hundred times the diameter of Earth. But a few stars leave the Sun in the dust. Antares, the bright orange heart of the scorpion, appears to be about 700 times bigger. If the Sun were the size of an NBA basketball, then Antares would be bigger than the entire arena.

That size may not be constant, though. The star’s brightness can vary by a fair amount. That suggests that Antares is unstable, so it pulses in and out. Some studies say its diameter could vary by as much as 20 percent. Not to bury you in numbers, but that would be the equivalent of roughly 140 Suns.

Other studies suggest it’s not the whole star that changes. The changes in brightness aren’t regular, so there’s no way to predict when Antares will get brighter or fainter. That could mean that bubbles of hot gas many times bigger than the Sun are churning to the surface. New bubbles are hot and bright, so they could account for the change.

No matter what’s going on, it’s certain that Antares is one of the more massive stars in the galaxy. That means it’ll get a lot brighter at the end of its life. It will explode as a supernova, perhaps outshining the entire galaxy before its tiny corpse fades into the cosmic night.

Look for Antares near the Moon in the early morning sky. It’ll stand to the left or lower left of the Moon at dawn tomorrow, and to the right of the Moon on Tuesday.
 

Script by Damond Benningfield