The merging galaxy Arp-Madore 417-391 comes into focus in this NASA/ESA Hubble Space Telescope image. The Arp-Madore catalog is a collection of particularly strange galaxies scattered across the southern sky and includes a collection of more spectacular colliding galaxies as well as subtly interacting galaxies. Located about 670 million light-years away in the southern celestial hemisphere in the constellation Eridanus, Arp-Madore 417-391 is one such galactic collision. The two galaxies were twisted by gravity and spun into a giant ring, leaving their cores side by side.

Hubble used the Advanced Search Camera (ACS), an instrument optimized for hunting galaxies and galaxy clusters in the ancient universe, to capture the scene. ACS Hubble has been contributing to scientific discoveries for 20 years and throughout its existence has been involved in everything from mapping the distribution of dark matter to studying the evolution of galaxy clusters.

This image is from a series of Hubble observations designed to create a list of interesting targets for later observations with the NASA/ESA/CSA James Webb Space Telescope and other ground-based telescopes. The astronomers selected a list of previously unobserved galaxies for Hubble to check out among other planned observations. Eventually, this will allow astronomers to make the most of Hubble’s limited observation time to create a zoo of interesting galaxies.