Hold on tight: in 4 billion years, we're due for a galactic collision!

The galaxy we live in, the Milky Way, is a large spiral galaxy that lives in a small cluster of other galaxies called the Local Group. The other big member is the Andromeda galaxy, located about 2.5 million light years away. That's a long way off, but we've known for a long time that Andromeda is heading more or less toward us at a speed of roughly 100 km/sec (60 miles/second). The question is, is it headed directly at us, or does it have some "sideways" motion and will miss us? New results announced today by astronomers using Hubble show that -- gulp! -- Andromeda is headed right down our throats! But don't panic. It won't happen for nearly 4 billion years.