Centaurus A . ... Credit Copyright: Tim Carruthers Explanation: Only 11 million light-years away, Centaurus A is the closest active galaxy to planet Earth. Spanning over 60,000 light-years, the peculiar elliptical galaxy, also known as NGC 5128 , is featured in this sharp color image. ... As in other active galaxies, that process likely generates the radio, X-ray, and gamma-ray energy radiated by Centaurus A . ... NASA Web Site Statements, Warnings, and Disclaimers . NASA Official: Jay Norris. ...