“They will crash into each other in a few million years”

NGC 6240

As the NASA caption to the larger image says, “This [wondrous] image of a pair of colliding galaxies called NGC 6240 shows them in a rare, short-lived phase of their evolution just before they merge into a single, larger galaxy.” The image was constructed from infrared light taken by Spitzer’s infrared array camera showing cold dust and radiation from star formation; visible light from Hubble (green and blue) showing hot gas and stars. Image credit: NASA/JPL-Caltech/STScI-ESA. From the NASA press release

The blob-like shape of the galaxy is due to the sustained violence of the collision. Streams of millions of stars are being ripped off the galaxy, forming wispy “tidal tails” that lead off NGC 6240 in several directions. But things are about to get even more violent as the main event approaches and the two galactic cores meld into one. In the center of NGC 6240, the two black holes in the cores will whip up a frenzy of radiation as they careen towards one another head-on, likely transforming the galaxy into a monster known as an ultra-luminous infrared galaxy, thousands of times as bright in infrared as our Milky Way.

But Don’t Panic! From the same NASA press release

The galactic cores are in a single, tangled galaxy called NGC 6240, located 400-million light years away in the constellation Ophiuchus. Millions of years ago, each core was the dense center of its own galaxy before the two galaxies collided and ripped each other apart. Now, these cores are approaching each other at tremendous speeds and preparing for the final cataclysmic collision.

They will crash into each other in a few million years, a relatively short period on a galactic timescale.