Don't worry about when the world as we know it might end. NASA has calculated that our entire Milky Way galaxy will crash into a neighboring galaxy with a direct head-on hit - in 4 billion years.
Astronomers in a NASA news conference Thursday said that years of observations from the Hubble Space Telescope provide grisly details of a long-anticipated galactic smashup. Astronomers had seen the Andromeda galaxy coming at us, but thought there was a chance that its sideways motion would make it miss or graze the Milky Way. Hubble readings now indicate that's not the case.