A clear night sky can be deceptively calm, stars shimmering across its inky blackness and the occasional meteor or satellite flitting across your field of view. But this serenity hides a violent universe where planets, asteroids, and comets move constantly, where stars are born and die in explosive supernovae, and black holes – the incredibly dense debris of dead stars – spin and collide, ripping apart spacetime itself.
Astronomers have a grandstand view of this dynamic cosmos every time they peer through their telescopes. But now technology has made it possible for any space enthusiast, too, to watch these cosmic events called transients (typically lasting fractions of a second to days or even years), with the help of nothing more than a smartphone.
