NASA says this is "the best ever image of the Antennae Galaxies." The fact is that new photograph is the best ever image of a galactic collision I've ever seen. The detail obtained by Hubble's Wide Field Camera 3—installed during a risky shuttle repair mission in 2009—is simply stunning. Zoooooom in!
This new image of the Antennae Galaxies shows obvious signs of chaos. Clouds of gas are seen in bright pink and red, surrounding the bright flashes of blue star-forming regions — some of which are partially obscured by dark patches of dust. The rate of star formation is so high that the Antennae Galaxies are said to be in a state of starburst, a period in which all of the gas within the galaxies is being used to form stars. This cannot last forever and neither can the separate galaxies; eventually the nuclei will coalesce, and the galaxies will begin their retirement together as one large elliptical galaxy.
NGC 4038 and NGC 4039 have been entangled in a titanic collision for a hundreds of millions of years. According to NASA, the "clash is so violent that stars have been ripped from their host galaxies to form a streaming arc between the two."
While Hubble took images of this collision in 1997 and 2006 with older instruments, they don't even approach the incredible detail and resolution of this new image taken by the Wide Field Camera 3. Zoom in and look at it—then notice the other galaxies floating around it.