Andromeda galaxy three times larger than thought

New measurements suggest the Andromeda galaxy, the nearest galaxy to our own Milky Way, is three times bigger than astronomers had thought. They discovered a thin sprinkling of stars once thought to be a halo is in fact part of the spiral galaxy's main disk.

The Andromeda galaxy is now estimated to be more than 220,00 light-years across, triple the previous estimate of 70,000 to 80,000 light-year.


An old picture of the Andromeda galaxy

A group of scientists studied the motions of about 3,000 stars and discovered they are not a halo but a part of the galaxy's disk. They found out that that the stars are sited in the plane of the Andromeda disk itself and move at a velocity which suggests they are in orbit around the center of the Andromeda galaxy. More info at Reuters