Hard to believe that this was once a pair of spiral galaxies. Undergoing a violent merger, the well-named Antennae Galaxies are quite a spectacle to radio telescopes. In blue are the data from the VLA, showing the trails of hydrogen stripped from the outer arms of the two spirals. In orange and gold (inset) are the data from ALMA showing the areas of star formation caused by the collision of gas and dust clouds.
Credit: B. Saxton (NRAO/AUI/NSF) from data provided by ALMA (ESO/NAOJ/NRAO) and NASA/ESA