A giant cloud of hydrogen gas is heading for a collision with our Milky Way Galaxy, and when it hits, it may set off a spectacular burst of stellar fireworks. The cloud, called Smith’s Cloud after the astronomer who discovered it, is 11,000 light-years long and 2,500 light-years wide and has enough hydrogen to make a million or so stars the size of the Sun. It’s only 8,000 light-years from our Galaxy’s disk and coming in at about 250 km/s. Don’t panic! It will hit 30,000 light years away from Earth—about 40 million years from now.
Image Credit: NRAO