"When stars die, they explode in a brilliant burst of light that releases more energy than our sun releases in its lifetime. This brilliant burst of light is so bright that for a brief moment can outshine an entire galaxy. Supernovas occur in our galaxy about once every 50 years. Put another way, somewhere in the universe, a star explodes every second."
Part 2 Of "The Cosmos" series for psdtuts+ free tutorial with over 400 screens and Hi Def video for each section. Take a peak hope you like it. http://psd.tutsplus.com/tutorials/painting/ringed-planet-supernova-photoshop/