I think we have properly established that colliding galaxies are some of the most gorgeous celestial features in the universe. If this point hasn't been emphasized enough, this is the perfect example to help whet your appetite for all things cosmic.
These exquisite beauties are NGC 1531 and NGC 1532, a pair of gravitationally interacting galaxies that call the Eridanus constellation their home. The largest of the two is NGC 1532, a spiral galaxy that appears almost edge on. Going on within the confines of this galaxy is a drastic increase in star formation activity, caused by the interactions between the two entities, which will soon become one. Most notably, this activity can be witnessed in the dusty spiral arms, where splotches of intense reddish regions color the area as if it were a canvas. The purple areas dotted about are also home to some of the most massive stars the galaxy has to offer.
The smaller galaxy, known as NGC 1531, appears as a mere distortion, as most of the galaxy has already been stripped of the bulk of its material. Now, all that's left of the dwarf galaxy are a small number of stars, with several plumes of gas and dust, which hoover above the central disk of NGC 1531.
The pair are about 50 million light-years distant, with the larger galaxy spanning about 100,000 light-years in diameter. Eventually, both will merge — leaving behind scant evidence of NGC 1531's existence.
See a larger image here.