|After its first close pass, Andromeda is tidally |
stretched out. The Milky Way, too, becomes
warped. Image released May 31, 2012.
Four billion years from now, the Milky Way galaxy as we know it will cease to exist.
Our Milky Way is bound for a head-on collision with the similar-sized Andromeda galaxy, researchers announced today (May 31). Over time, the huge galactic smashup will create an entirely new hybrid galaxy, one likely bearing an elliptical shape rather than the Milky Way's trademark spiral-armed disk.
"We do know of other galaxies in the local universe around us that are in the process of colliding and merging," Roeland van der Marel, of the Space Telescope Science Institute in Baltimore, told reporters today. "However, what makes the future merger of the Andromeda galaxy and the Milky Way so special is that it will happen to us."
Astronomers have long known that the Milky Way and Andromeda, which is also known as M31, are barrelling toward one another at a speed of about 250,000 mph (400,000 kph). They have also long suspected that the two galaxies may slam into each other billions of years down the road. [Milky Way Slams Into Andromeda (Artist Images)]
However, such discussions of the future galactic crash have always remained somewhat speculative, because no one had managed to measure Andromeda's sideways motion — a key component of that galaxy's path through space.
But that's no longer the case.
Van der Marel and his colleagues used NASA's Hubble space telescope to repeatedly observe select regions of Andromeda over a seven-year period. They were able to measure the galaxy's sideways (or tangential) motion, and they found that Andromeda and the Milky Way are indeed bound for a direct hit.
"The Andromeda galaxy is heading straight in our direction," van der Marel said. "The galaxies will collide, and they will merge together to form one new galaxy." He and his colleagues also created a video simulation of the Milky Way crash into Andromeda.