When Galaxies Collide

By Laura Boness

It may look beautiful, but collisions between galaxies are a messy business.

Just a few hundred million years ago, NGC 2936 (top) was a normal star-forming spiral galaxy. But then it got too close to its elliptical companion NGC 2937 (lower left) and became distorted.

The orbits of the spiral galaxy’s stars have become scrambled as it interacts with the gravitational tide of the elliptical galaxy. This has warped the spiral and caused interstellar to emerge. The dust and gas drawn from NGC 2936 is being compressed, which in turn is triggering star formation. The new stars can be seen as blue dots on the distorted arms.

NGC 2937, however, doesn’t seem to be much affected by the gravitational pull from its neighbor. There is little gas or dust present and most of the stars within the galaxy are old, as they are red rather than blue.

In a billion years or so, the two will probably merge and form one larger galaxy.

Source [NASA]