Spica is already one of the brightest stars in the Milky Way. In the next few million years, though, it’ll get a lot brighter — only a few stars in the entire galaxy will outshine it. Spica is in good view low in the east at dawn right now. Tomorrow, it stands close to the right of the planet Mercury, which looks a good bit brighter than Spica. What we see as Spica is actually the combined light of two stars, both of which are much bigger, brighter, and heavier than the Sun. The more prominent member of the duo is about 2,000 times brighter than the Sun at visible wavelengths. That star is nearing the end of its “normal” lifetime. Soon, it will stop fusing together the hydrogen atoms in its core to make helium. Instead, it’ll fuse the helium to make even heavier elements. In response, the star’s outer layers will puff up, making the star much bigger than it is today — a stellar supergiant. That’ll also make it much brighter than it is today — many thousands of times brighter than the S
