Galaxies Collide!

This photo shows two large galaxies colliding 400 million light years away.

The Spitzer Telescope's image of Galaxy NGC 6240, which is 400 million light-years away in the constellation Ophiuchus, highlights the bursts of infrared radiation as the dust and gas from the two galaxies slam together. All that pressure creates new generations of hot stars, blazing away in infrared wavelengths even though the radiation in visible wavelengths is obscured by dust clouds. Because of this phenomenon, these starry swirls are known as luminous infrared galaxies.

In the news release, the Spitzer science team point to the streams of stars being ripped off the galaxies - "tidal tails" that extend into space in all directions. And this is just the warmup act: Bush and her colleagues expect the galactic black holes to hit head-on. That would upgrade NGC 6240's status to that of an ultra-luminous infrared galaxy, thousands of times as bright in infrared as our own Milky Way.