Galaxies are big, but not big enough not to be devoured by others of their kind. Our home galaxy, the Milky Way will eventually be swallowed by its nearest neighbour, Andromeda. The two galaxies race towards each other with the speed of roughly 500'000 km/h. No worries, though, scientists estimate that in about two billion years Earth and the rest of our solar System have a new home in the outskirts of Andromeda.
In a celebration of Hubbles' 18th birthday, NASA and ESA just published a series of pictures which show colliding and merging galaxies: www.spacetelescope.org
