This colliding trio — known to astronomers as SDSSCGB 10189 — is a relatively rare combination of three large star-forming galaxies lying within only 50,000 light-years of one another. While that might sound like a safe distance, for galaxies this makes them extremely close neighbors! Our own galactic neighbors are much further away; Andromeda, the nearest large galaxy to the Milky Way, is more than 2.5 million light-years away from Earth. This observation was designed to help astronomers understand the origin of the largest, most massive galaxies in the universe. These galactic behemoths are called Brightest Cluster Galaxies (BCGs) and — as the name suggests — are defined as the brightest galaxies in any given galaxy cluster. Astronomers suspect that BCGs form through the merger of large, gas-rich galaxies like the ones in this image. They turned to Hubble’s Wide Field Camera 3 (WFC3) and Advanced Camera for Surveys (ACS) to investigate this galactic trio in painstaking detail, hoping to shed light on the formation of the Universe’s most massive galaxies.
