Using the Hubble Space Telescope, astronomers have detected a multi-tailed main-belt comet the likes of which has never been seen before.
A main-belt comet is a special class of celestial objects that orbit inside our asteroid belt and exhibit comet-like activity at some point during their orbits (like shedding some of its mass and having tails). NASA defines it as an object with a distance of more than 2 AU but less than 3.2 AU from the Sun (1 AU being the average distance of the Earth to the Sun). The first MBC was discovered in 1979, and it was initially thought to be an asteroid. But astronomers Eric Elst and Guido Pizarro noticed it had a tail in 1996. There are currently 11 known main-belt comets in our solar system, including PANSTARRS.