"We were literally dumbfounded when we saw it," astronomer David Jewitt with the University of California at Los Angeles, said in a statement. "It's hard to believe we're looking at an asteroid."
Asteroids normally have no tails.
The asteroid, known as P/2013 P5, first appeared as a fuzzy point of light in a sky survey by the Pan-STARRS 1 telescope in Hawaii in August.
In September astronomers used the sharp-eyed orbiting Hubble telescope to zero in on the object, located in the main asteroid belt between Mars and Jupiter.
Not only is the asteroid sporting six tails, follow-up observations 13 days later showed it had changed shape.
Scientists suspect pressure from photons, small particles of light or electromagnetic radiation, in sunlight is causing the asteroid to spin faster, disrupting its surface.
Computer models show the dust plumes likely started rising off the asteroid's surface in April 2012, according to Jessica Agarwal, with the Max Planck Institute in Lindau, Germany.
"P/2013 P5 might be losing dust as it rotates at high speed," Agarwal said in a statement. "The sun then drags this dust into the distinct tails we're seeing."
Astronomers intend to keep a lookout for signs the asteroid is breaking up, a process they suspect is common, but never before observed.
"This is just an amazing object to us, and almost certainly the first of many more to come," Jewitt said.
The research appears in this week's issue of The Astrophysical Journal Letters.