Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Supernovae are extremely powerful and luminous stellar explosions and cause a burst of radiation that often briefly outshines an entire galaxy, before fading from view over several weeks or months. During this short interval a supernova can radiate as much energy as the Sun is expected to emit over its entire life span. The explosion expels much or all of a star's material at a velocity of up to 30,000 km/s (10% of the speed of light), driving a shock wave into the surrounding interstellar medium. Learn more about supernovae, their causes and effects as well as their role in the universe in this book.