Centaurus A . ... Credit Copyright: . ... Image Data: Hubble Space Telescope , European Southern Observatory Explanation: What's the closest active galaxy to planet Earth? ... The colorful galaxy portrait is a composite of image data from space- and ground-based telescopes large and small. ... As in other active galaxies , that process generates the radio, X-ray, and gamma-ray energy radiated by Centaurus A. Authors editors: Robert Nemiroff ( MTU ) Jerry Bonnell ( USRA ) . ...