A new "main-belt comet" — a comet-like object masquerading as an asteroid in the asteroid belt between Mars and Jupiter — has been identified, bringing the tally of these beguiling objects up to 14.
Along with "dark comets," which scientists think make up 60% of all near-Earth objects, main-belt comets belong to a broader population with the umbrella moniker of "active asteroids." In general, all of these objects are on orbits typical of asteroids, but they display signs of activity — in particular, they exhibit "outgassing" to form a coma and a tail just like a comet. They therefore blur the lines between rocky asteroids and icy comets, showing that pigeon-holing such bodies as one or the other can be a futile effort.
