Scientific American explores the eventual collision of the Milky Way and the Andromeda Galaxy. Can you imagine the traffic snarl to have a look at that wreckage?

“First of all the Milky Way galaxy is big. As spiral galaxies go it’s in the upper echelons of diameter and mass. In the relatively nearby universe, it and our nearest large galaxy, Andromeda, are the sumo’s in the room. This immediately makes it somewhat unusual, the great majority of galaxies in the observable universe are smaller. The relationship to Andromeda is also very particular. In effect the Milky Way and Andromeda are a binary pair, our mutual distortion of spacetime is resulting in us barreling together at about 80 miles a second. In about 4 billion years these two galaxies will begin a ponderous collision lasting for perhaps 100 million years or so. It will be a soft type of collision – individual stars are so tiny compared to the distances between them that they themselves are unlikely to collide, but the great masses of gas and dust in the two galaxies will smack together – triggering the formation of new stars and planetary systems.”