Over a span of 19 years, the Hubble Space Telescope has snapped scores of fascinating images of galaxies colliding with one another. This picture was issued to celebrate the 19th anniversary of the launch of the Hubble aboard the space shuttle Discovery in 1990. Pictured is a trio of galaxies, called Arp 194. The bright blue streamer is a stretched spiral arm full of newborn blue stars, which typically occurs when two galaxies interact and gravitationally tug at each other. The two nuclei of the colliding galaxies can also be seen in the process of merging at the upper left. The blue bridge looks like it connects to a third galaxy, but this galaxy is actually in the background and not connected at all. Hubble's sharp view lets astronomers visually sort out what are foreground and background objects when galaxies appear to overlap. During the past 19 years, Hubble has made more than 880,000 observations and recorded more than 570,000 images of 29,000 celestial objects.

Image courtesy of NASA, ESA, and the Hubble Heritage Team (STScI/AURA)