"Mysterious Comets" Near Earth!

Scientists from the University of Michigan have discovered that about 60 percent of near-Earth celestial bodies may be dark comets, which are mysterious asteroids that contain ice or once contained it. The journal Icarus notes that "these comets simultaneously possess characteristics of both asteroids and comets. They are located close to the sun, allowing the ice to turn directly into gas, forming a cloud around them and giving them acceleration that is not related to gravity." Astronomers studied seven known dark comets and estimated that between 0.5 to 60 percent of near-Earth objects could be dark comets lacking a halo, but exhibiting acceleration not tied to gravity. They are believed to originate from the inner asteroid belt, where the bodies contain ice. Researchers suggest that these comets begin to rotate rapidly after losing their ice, which may lead them to break apart into small bodies that continue to lose ice and accelerate. This explains their small size and high rotational speed.