Looking like a stellar sea turtle, the galaxy known as NGC 6240 is actually the result of two smaller galaxies that started merging 30 million years ago.
The collision triggered a bout of star formation and sparked numerous supernova explosions. X-ray images of the peculiar galaxy also revealed two giant black holes about 3,000 light-years apart that will eventually join together.
NGC 6240 sits about 400 million light-years away in the constellation Ophiuchus.
Image by NASA, ESA, the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration and A. Evans (University of Virginia, Charlottesville/NRAO/Stony Brook University), K. Noll (STScI), and J. Westphal (Caltech)