Imagine the drama when two objects, each containing billions of times the mass of our sun, collide at speeds of several hundred miles per second. That's what you are seeing in the above images. Two galaxies, 60 million light-years away, have had a near head-on collision and are believed to be merging into a single galaxy.
This collision has disturbed the gas in both of the galaxies, compressed it, and triggered the formation of large numbers of stars. An image taken with the Infrared Space Observatory (ISO) shows that the regions of the most copious star formation lie in a ring around the center of one of the galaxies and along a bar that connects the two galaxies (left image). An enlarged ground-based view shows a string of bright knots in the star-forming regions. The knots are clouds of gas illuminated by clusters of very hot, young stars.
The collision between the galaxies threw off gas along two narrow curved tails that extend well beyond the above images. One of the tails can just barely be seen in the infrared image. In long-exposure photographs, the tails look like a giant insect's antennae and are the reason for the galaxies' name, the Antennae.
Check out other observations in the Observation of the Week Archive.