The discovery was so unusual that at first astronomers didn't know what to call it. A comet bearing the official name C/2014 S3 also bore no tail—which isn't just unusual, but the first ever to be observed by humans, reports Reuters. Moreover, it was dark and rocky, like an asteroid. "I had never heard of such a thing," Karen Meech of the University of Hawaii tells New Scientist. "We wondered, what are we going to call this? 'Potentially dead comet' is too much of a mouthful." They opted instead for "Manx" comet, after the famous type of cat with no tail. Like the Manx cat, it technically has a little stub of a tail, though the team says it comprises mostly dust.
The comet is as much as 100,000 times "less active" than most comets on similar orbits, reports Space.com, which explains that a comet's activity increases as it nears the sun and its ice heats into a gas that becomes the comet's tail. C/2014 S3's low activity suggests it has little ice, which is unusual for comets that hail from where it is believed to come from: the Oort cloud. The team surmises that the comet was flung there from the inner solar system soon after the birth of the solar system. "We may be looking at fresh inner solar system Earth-forming material that was ejected from the inner solar system and preserved for billions of years in the Oort cloud," they report in the journal Science Advances. (Check out what the destruction of a family of comets appears to have done.)