... Ganymede: The Largest Moon in the Solar System . ... A jet stretching nearly a million light years has been imaged emanating from galaxy Pictor A. The thin jet of electrons and protons shoots out at nearly light-speed likely from the vicinity of a large black hole at the galaxy center. ... The Last Moon Shot . ... APOD is Five Years Old Today . ... What can 100,000 galaxies tell you? ... The Keyhole Nebula in Infrared . ... A Bubbling Galaxy Center . ... What's happening in the center of this galaxy...