Farthest Stars

Most of the stars that are visible to the eye alone are no more than a few hundred light-years away — with the most distant at only a few thousand light-years. Yet the Milky Way extends well beyond that range. The far edge of the galaxy’s disk is at least 75,000 light-years away, and perhaps a good bit farther. And the Milky Way’s halo — a thinly populated region that surrounds the disk — extends hundreds of thousands of light-years in every direction.

A recent study found a star in the halo that’s the farthest member of the Milky Way yet seen. It’s a million light-years away from Earth.

An international team studied a class of pulsating stars in and around the constellation Virgo. The stars are named for their prototype, RR Lyra. Such stars are big and bright, and they’re near the ends of their lives. They pulse in and out, getting brighter and fainter with each pulse. The way such a star’s light changes reveals the star’s true brightness. Astronomers use that to calculate its distance.

The team discovered a couple of hundred such stars, which help astronomers map the galaxy. Eight of the stars are at least three-quarters of a million light-years away, with one at a cool million — the most-distant member of the Milky Way ever seen.

Virgo is well up in the southeast at nightfall. It’s marked by its leading light, Spica. The distant star is much too faint to see without a telescope — lost in the fringes of the Milky Way.

Script by Damond Benningfield