SPIRAL ASTEROID: On Dec. 12th, the International Astronomical Union issued a telegram (CBET nr.2583) announcing the discovery of a spiral structure around main belt asteroid (596) Scheila. Steve Larson of the Catalina Sky Survey (CSS) found the curious shape in images obtained Dec. 11th through the Catalina 0.68-m Schmidt telescope. Other observers have since confirmed the phenomenon. The following picture was taken on Dec. 12th by Italian astronomers Ernesto Guido and Giovanni Sostero using a remotely-controlled 0.25m telescope in New Mexico:

What's going on? There are at least two possibilities. (1) A small asteroid might have hit 596 Scheila, raising a cloud of dust which forms a nebula around larger space rock. A 1-meter class impactor could be large enough to do the trick. (2) 596 Scheila might be a rare main belt asteroid, a body with the orbital characteristics of an asteroid and the physical characteristics of a comet. If so, a pocket of volatile ice might be vaporizing to produce the spiraling tail.

How the nebula or tail evolves in the days ahead could provide important clues. Amateur astronomers with experience in asteroid imaging are encouraged to monitor developments.
[link to spaceweather.com]

Spirals and dusty plasma, hmmm. Wonder what's going on, the asteroid is between the orbit of Mars and Jupiter. [link to ssd.jpl.nasa.gov]