Astronomers Puzzle Over Newfound Asteroid That Acts Like a Comet [Video]: Scientific American

Astronomers Puzzle Over Newfound Asteroid That Acts Like a Comet [Video]: Scientific American:

 The distinction between comets and asteroids is in principle a clear one, encoded right in the words themselves. Both terms come from Greek roots—“comet” descends from a word meaning “long-haired” and “asteroid” means, roughly, “starlike.” So there it is: comets are fuzzy, and asteroids are discrete pinpricks of light. The definitions hint at compositional differences as well: comets are icy, which leads them to come apart when they draw near the sun, whereas rocky asteroids are somewhat more robust.