To celebrate the 19th anniversary of the Hubble Space Telescope this week, a stunning picture of two galaxies merging has been released. The merging galaxies are in the upper parts of the image, and they have an impressive trail of blue star-forming regions. Remarkably, the galaxy in the bottom of the picture is not merging with any of the galaxies in the upper part of the picture: it just happens to be in the background. This would have been hard to tell without the resolution of the Hubble Space Telescope, which reveals dust clouds around the trail that obscures the galaxy in the background.
Arp 194 and its cosmic fountain