... Tonight's Sky . ... Observing . ... Supernova showered Earth with radioactive debris . ... The double star 54 Leonis, spiral galaxy NGC 3198, and emission nebula NGC 3199 . ... Asymmetric ashes . ... A stronomers are reporting remarkable new findings that shed light on a decade-long debate about one kind of supernova, the explosion that marks a star's final demise: does the star die in a slow burn or with a fast bang? ... Only registered members of Astronomy.com are allowed to comment on this...