This composite image of the Whirlpool Galaxy and it’s nearby companion galaxy overlays radio astronomy data from the Very Large Array with optical data. The image in white shows how the galaxies appear to optical telescopes: one giant spiral galaxy with a smaller one hanging off an arm. The VLA sees a much bigger picture. The blue overlay reveals the the cast-off gases that were once in the outer spiral arms of these galaxies which have been pulled apart as the smaller galaxy has moved passed the larger one.
Image Credit: NRAO