... They're all planetary nebulae of course, glowing gaseous shrouds shed by dying sun-like stars as they run out of nuclear fuel. Neptune: Still Springtime After All These Years . ... In the 1960s spring came to the southern hemisphere of Neptune, the Solar System's outermost gas giant planet. ... The formation of a black hole from the collapsing core of a massive star is thought to be heralded by a spectacular supernova explosion. ... APOD: 2003 June 9 Ш The Pencil Nebula Supernova Shockwave . ...