See that little, growing white dot? That's the youngest supernova ever discovered and the closest to Earth in a generation.
The lucky Galileio to spot this momentous event was The Palomar Transient Factory, an automated system mounted on the 48-inch Samuel Oschin Telescope in Southern California. As it scans the night sky, the PTF transmits the collected data to the National Energy Research Scientific Computing Center where a cadre of of supercomputers apply advanced computer-learning search algorithms to analyze and identify potentially important objects. Coordinates to these points are then distributed to astronomers worldwide for further inspection.
PTF 11kly—as the supernova has been ID'd—is a Type Ia located in the the Pinwheel Galaxy, part of the Big Dipper constellation about 21 million light years away. That's unfortunately too far away to see with the naked eye but luckily too far away to pose any threat to the planet. It's just the fifth Type Ia supernova to explode this close to the Earth since 1572. To find one just a few hours after it went critical is unheard of and will provide invaluable insight into how they develop.
Type Ia supernovae are formed when White Dwarves—a star that's already burned through its fuel and ceases fusion—undergo a secondary fusion reaction after siphoning material off a companion star, releasing massive amounts of enrgy. These supernovae are incredibly valuable to science because the peak luminosity between these types of supernova is so uniform that they can be used as standard candles in measuring interstellar distances.