Collisions play an important role in galaxy evolution. These two galaxies -- the Whirlpool and its companion -- are relatively nearby at a distance of just 23 million light-years from Earth. IRAC sees the main galaxy as very red due to warm dust -- a sign of active star formation that probably was triggered by the collision.
April 19, 2012 10:35 AM PDT
Photo by: NASA / JPL-Caltech / R. Kennicutt (Univ. of Arizona)