Milky Way may escape fated collision with Andromeda galaxy
By Daniel Clery, Science.
Excerpt: 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.... ...It wasn’t until the era of orbiting observatories that astronomers could judge Andromeda’s overall velocity in 3D.... It was, they calculated, heading pretty much straight at the Milky Way at a speed of 110 kilometers per second. ...A study from 2008 suggested a Milky Way–Andromeda merger was inevitable within the next 5 billion years...ending up in...the resulting elliptical, which the researchers dub “Milkomeda.” The Milky Way, seen today as a bright band across the sky, would be replaced by a “milky blob” marking the dense core of the new galaxy.... ...even if the two galaxies escape collision this time, it is gravity that will eventually have the last word. All the galaxies in the Local Group are bound together gravitationally, and so over tens of billions of years, they will all end up piling on top of each other into a single giant elliptical galaxy. Meanwhile, if the accelerating expansion of the universe continues unabated, all other galaxies will disappear beyond our cosmic event horizon, leaving Milkomeda as the sole occupant of the visible universe....