This artist's conception of the Milky Way shows the four-arm spiral structure confirmed by recent VLBA distance measurements (shown by green and blue dots). The data show that the Milky Way is spinning faster than previously believed. Our galaxy therefore is more massive than astronomers thought, matching Andromeda's heft. Red dots mark the galactic center and the location of our solar system.
IPAC-Robert Hurt/ CfA-Mark Reid/NRAO/AUI/NSF