For years, astronomers thought it was the Milky Way’s destiny to collide with its near neighbor the Andromeda galaxy a few billion years from now. But a new simulation finds a 50% chance the impending crunch will end up a near-miss, at least for the next 10 billion years.

It’s been known that Andromeda is heading toward our home Galaxy since 1912, when astronomer Vesto Slipher noted that its light is blue-shifted—squashed toward shorter wavelengths by the Doppler effect, in the same way that an oncoming ambulance siren whines with a higher pitch. At the time, Andromeda’s true size and distance were not known; many thought that galaxies were “nebulae” in the vicinity of the Milky Way. It wasn’t until the era of orbiting observatories that astronomers could judge Andromeda’s overall velocity in 3D based on the motions of many of its stars. It was, they calculated, heading pretty much straight at the Milky Way at a speed of 110 kilometers per second.