Seven New Dark Comets Discovered In Our Solar System - Earth.Com

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Dark comets have become a buzzworthy subject among astronomers since researchers announced the discovery of seven additional examples of these mysterious objects.

In direct observations, they seem to behave like asteroids, but accelerate in ways that make them act like comets. The newfound group doubles the tally of known dark comets to fourteen, causing excitement and questions about what might lurk behind their secretive surfaces .

Dark comets first drew attention when a near-Earth object defied the expectations set by ordinary asteroids. In most cases, tiny effects like sunlight heating an asteroid's surface account for small changes in its path.

However, the unexpected shift these objects displayed hinted at a different story. Scientists kept an eye on them and, in 2017, a major clue appeared in the form of 1I/2017 U1 ( 'Oumuamua ), which looked like an asteroid but moved as if gas was pushing on it.

That puzzling find nudged researchers to ask whether they had encountered a new type of comet altogether.

Not long after those early revelations, astronomers noticed a small group of objects that resembled asteroids yet behaved like comets .

Davide Farnocchia of NASA's Jet Propulsion Laboratory in Southern California described one of these oddities in vivid terms. 

"When you see that kind of perturbation on a celestial object, it usually means it's a comet, with volatile material outgassing from its surface giving it a little thrust," said Farnocchia.

Darryl Seligman, a postdoctoral fellow in the Department of Physics at Michigan State University in East Lansing, took a particular interest in their unusual orbits and appearances.