Stephan's Quintet

A fascinating and well-studied group of galaxies in the Pegasus Constellation, Stephan's Quintet is so named for the man who discovered while working at the Marseilles Observatory in 1976, Édouard Jean-Marie Stephan.

Comprising five galaxies, Stephan's Quintet is also part of the Hickson Compact Group (HCG) 92, which also includes a sixth galaxy, NGC 7320C, visible near the top of the frame. In the image, NGC 7320C looks like it's interacting with NGC 7230, the blue-pink galaxy on the left. But this is an optical illusion. NGC 7320 is only about 40 million light years away while NGC 7320C and the remaoning galaxies in the Quintet are 290 million light years away.

The central formation, NGC 7319, is really two galaxies—NGC 7319A (the lower one) and NGC 7319B (the upper galaxy. NGC 7319B is actually crashing into the group forming showckwaves that are visible in the image above and to the right of it. NGC 7320C is on a similar trajectory—just passing through.