The Mysterious Comets That Hide in the Asteroid Belt

As with other comets, the ices of a main-belt comet vaporize and create a coma as it screeches past the sun. But strangely, they orbit in the asteroid belt, a graveyard of debris They didn’t merge into planets.

The first main belt comet was discovered in 1996, but “you can always explain a weirdo,” Dr. Snodgrass said, suggesting that the belt could have captured an interloper comet. However, since then another eight have been detected. About 20 other belt-tethered objects seen losing mass, possibly due to periodic comet-like ice vaporization, wild spinning, or recent asteroid impacts, are considered candidates to be comets.

The study researchers, hoping to spot more mavericks in the main belt, found only one new candidate: 2001 NL19.

“This is the only one that seems to have something on it,” Ms Ferellec said, describing the object’s faint tail shape as it recedes from the sun. It could have been born from the vaporization of ice, turning the object into a cometary. More observations will be needed as it gets closer to the sun again, when a coma or tail is more likely to appear.

Regardless of how 2001 NL19 is classified, the number of confirmed main-belt comets suggests that “these things are native to the asteroid belt,” said Dr. Snodgrass. The genesis of it remains unclear, although some ideas have been put forward.

Perhaps main belt comets, like their more distant conventional counterparts, formed far from the sun during the chaotic early days of the solar system, but instead of staying far away, they were pushed by the gravity of other objects and placed on the which is now the asteroid. belt. After billions of years, any surviving primordial ice would be buried deep within their rocky surfaces. If they are hit by another asteroid, some of these the ice will be excavatedexposing it to the scorching light of the stars.

Uncertainties aside, one thing is clear: the existence of these wacky asteroid-comets complicates the need to put natural phenomena into neat little boxes.

“I always say, ‘Everything is a comet,'” said Kacper Wierzchos, an astronomer at the University of Arizona Lunar and Planetary Laboratory who was not involved in the study. “If you put my sofa close enough to the sun, it would start to melt and I would go into a coma.”