... Springtime on Mars . ... The Gum Nebula Supernova Remnant . ... Because the Gum Nebula is the closest supernova remnant, it is actually hard to see. ... Spiral Galaxy In Centaurus . ... Centaurus, the Centaur, is one of the most striking constellations in the southern sky. ... A Crescent Nebula Star Field . ... What caused the Crescent Nebula? Looking like an emerging space cocoon, the Crescent Nebula, visible on the right, was created by the brightest star in its center. ...