Our Galaxy is about to collide with Andromeda!

In case you didn't know, in a mere 3 billion years, the Milky Way and Andromeda, both spiral galaxies, will collide, to create a hybrid galaxy. As New Scientist wrote last year, "Our collision with Andromeda will have a spectacular climax. At the centre of the Milky Way is a giant black hole more than 3 million times the mass of the sun. Another in Andromeda is probably 10 times the size. These two black holes will settle towards the centre of the new galaxy, and there they will spiral together and eventually merge. The energy released will be tremendous, sending out a blast of light and X-rays, and a pulse of gravitational waves that will squeeze and stretch every star and planet." See the MPEG simulation of the collision.