Astronomers Think They Have a Warning Sign for When Massive Stars are About to Explode as Supernovae
Red supergiant stars are explosions waiting to happen. They are in the last stage of their life, red and swollen as they fuse heavier elements in a last effort to keep from collapsing. But eventually, gravity will win and the red supergiant core will collapse, triggering a supernova. We know it will happen, but until recently, we didn’t know when.

