Hydra A is a galaxy cluster that is 840 million light-years from Earth. The cluster gets its name from the strong radio source, Hydra A, that originates in a galaxy near the center of the cluster.
Optical observations show a few hundred galaxies in the cluster.
Chandra X-ray observations reveal a large cloud of hot gas that extends throughout the cluster. The gas cloud is several million light-years across and has a temperature of about 40 million degrees in the outer parts decreasing to about 35 million degrees in the inner region.