Mapping the milky way [2013 Tech To Watch]

Astronomers who study the Milky Way don't have it easy. Bound to the solar system, they're on the inside looking out, all the while whipping around the galactic center at roughly 900 000 kilometers per hour. That's made it more than a little tricky to pin down fundamental details. It's still unclear, for example, how massive the Milky Way is and whether it's on a collision course with the nearby Andromeda galaxy. And there's still a lot of uncertainty about its basic structure. "There's been a pretty active debate in the last couple of years whether there are two or four spiral arms," says Mark Reid, a radio astronomer at the Harvard-Smithsonian Center for Astrophysics, in Cambridge, Mass. "That's pretty basic."