The remains of an exploded star glow brightly in X-rays (blue) and visible light in this composite image from two space telescopes. Known as a supernova, the exploding star produced a torrent of energy and charged particles. If such an explosion happened close to Earth it could zap our planet, perhaps even triggering mass extinctions. Fortunately, no future supernova is within the danger zone. [NASA/CXC/Rutgers/J.Hughes; NASA/STScI]