El Gordo: a massive distant merging galaxy cluster

This picture of the galaxy cluster ACT-CL J0102−4915 combines images taken with ESO’s Very Large Telescope with images from the SOAR Telescope and X-ray observations from NASA’s Chandra X-ray Observatory. The X-ray image shows the hot gas in the cluster and is shown in blue. This newly discovered galaxy cluster has been nicknamed El Gordo — the "big" or "fat one" in Spanish. It consists of two separate galaxy subclusters colliding at several million kilometres per hour, and is so far away that its light has travelled for seven billion years to reach the Earth.