Cosmic Cloud on Collision Course

It's large, it's fast, and it's heading toward the Milky Way. Less than 40 million years from now, a giant cloud of hydrogen gas, clocked at 250 kilometers per second, will smash into our home galaxy, likely setting off a huge burst of star formation. In fact, the cloud contains enough gas to form a million stars like our sun, astronomers reported. The crash will happen far from us, but it could still put on quite a show as the cloud's gas condenses into tens of thousands of bright, massive stars that will explode as supernovas within a couple of million years.