On Thursday, NASA scientists announced that after scouring reams of data from the Hubble Space Telescope they can say with certainty that our Milky Way is destined to eventually collide with our neighbor the Andromeda galaxy. Of course, it won’t happen for about 4 billion years, but it can’t hurt to be prepared.
We’ve known that Andromeda, called M31, has been moving toward our galaxy for quite some time, drawn by the force of gravity between the two collections of stars.  However, whether or not the two galaxies would actually collide was still up for debate. Now, it seems to be all but certain. NASA quotes Sangmo Tony Sohn of the Space Telescope Science Institute as saying:
“After nearly a century of speculation about the future destiny of Andromeda and our Milky Way, we at last have a clear picture of how events will unfold over the coming billions of years[.]”
Andromeda is currently 2.5 million light-years from Earth, but moving at a pretty swift 250,000 miles per hour. At that speed, the collision won’t be happening until about 4 billion years from now. NASA says that their data suggests that Andromeda’s tangential — or “sideways” — motion is such that the Milky Way will experience a head-on collision from the neighboring galaxy.
Interestingly, there’s a chance that this celestial merger will also involve Triangulum galaxy, a companion to Andromeda that might come along for the ride.
The end result of the collision has a lot more to do with orbits and distribution of stars than it does galactic cataclysm. In fact, the distance between stars is such that its extremely unlikely that any star would collide with any other star. However, the shape of our space-neighborhood will be changed forever. According to Gurtina Besla of Columbia University, NY a head-on collision would result in:
“The stellar populations of both galaxies are jostled, and the Milky Way loses its flattened pancake shape with most of the stars on nearly circular orbits. The galaxies’ cores merge, and the stars settle into randomized orbits to create an elliptical-shaped galaxy.”
Closer to home, a galactic collision could push our solar system even further from the current galactic core, or eject our home star entirely. This would, however, be of little consequence to the solar system.
The kicker to all this is that we’ll probably be long dead anyway. In about 1.4 billion years, the Sun will be so bright and hot that it will be impossible for liquid water to exist on the planet. So unless we get off our backsides and become a multiplanet species, galactic collisions are the least of our concerns.
(via NASA, Wikipedia, artistic renderings of the impending galactic collision via Hubble)
- Too bad we won’t end up like this “emerald cut galaxy”
- Only four billion more years to catch a view like this
