The Geminid meteor shower, which peaks each year in December... are *not* caused by debris left behind from an active comet... Until recently, the favored view of Phaethon was that it's a dead comet -- the rocky core of a "dirty snowball" that lost its ices after too many close encounters with the sun. ... In June 2009 astronomers using the STEREO sun-watching probe suddenly saw the rocky body flare to life as it neared the sun, brightening by a factor of two... So, not so dead after all. But that brings us back to figuring out what exactly Phaethon...