NASA's Swift satellite has acquired the highest-resolution view of the neighbouring spiral galaxy M31. Also known as the Andromeda Galaxy, M31 is the largest and closest such galaxy to our own. It's more than 220,000 light-years across and lies 2.5 million light-years away in the constellation Andromeda. Dense clusters of hot, young, blue stars sparkle in the disk beyond the galaxy's smooth, redder central bulge. Star clusters are especially plentiful along a ring about 150,000 light-years across.