Mystery Object Behaves Both Like a Comet and Asteroid

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Something awfully curious is happening 250 million miles away in the asteroid belt.

Astronomers think they may be witnessing a never-before-seen collision between two asteroids.

The puzzle centers on a newly discovered object that superficially looks like a comet but lives among the asteroids.

The strange object was discovered on January 6

by the Lincoln Near-Earth Asteroid Research (LINEAR) sky survey. The

object appears to be in an orbit inside the main asteroid belt — not a

place where comets usually dwell.

The distinction? Comets swoop along elliptical orbits close in to the sun and grow long gaseous and dusty tails as ices sublimate off their solid nucleus and release dust. But asteroids are mostly in more circular orbits and are not normally expected to be as volatile as comets.

In the comments below veteran comet observer Jim Scotti correctly points out that several other weird comet/asteroid hybrids have been reported over the years.

But there is high excitement this time because astronomers following the object are reasonably convinced that for the first time ever they have a ringside seat to watching an actual hypervelocity collision between two previously unseen asteroids. The asteroid belt is littered with debris from ancient shattering collisions, but astronomers have never before seen a head-on smashup in the works.

In the previous cases an asteroid containing ices may have experienced a short-lived outburst. Or, a fragile icy and stony nucleus simply came unglued and the remnants are being scattered by the pressure of the solar wind.

(Perhaps extraterrestrials are playing a real version of the popular 1980's arcade game "Asteroids.")

No doubt there will be many more observations of this evolving phenomenon in the near future, so stay tuned.

Photo Credit: Spacewatch/U of Arizona