WASHINGTON (Reuters) - The Andromeda galaxy just got bigger -- three times bigger, astronomers said on Monday. The galaxy is not actually expanding. But new measurements suggest that the nearest galaxy to our own Milky Way is three times broader than astronomers had thought. They now believe a thin sprinkling of stars once thought to be a halo is in fact part of Andromeda's main disk. That makes the spiral galaxy, so close to Earth that it appeared as a fuzzy blob to the ancients, more than 220,000 light-years across -- triple the previous estimate of 70,000 to 80,000 light-years....