Asteroid Phaethon s Comet-Like Tail Not Made Of Dust But Gas Handout photo - This illustration depicts asteroid Phaethon being heated by the Sun. The asteroid?s surface gets so hot that sodium inside Phaethon?s rock likely vaporizes and vents into space, causing it to brighten like a comet and form a tail. We have known for a while that asteroid 3200 Phaethon acts like a comet. It brightens and forms a tail when it?s near the Sun, and it is the source of the annual Geminid meteor shower, even though comets are responsible for most meteor showers. Scientists had blamed Phaethon?s comet-like behavior on dust escaping from the asteroid as it?s scorched by the Sun. However, a new study using two NASA solar observatories reveals that P