'Lazarus' Comets Rekindled from 'Comet Graveyard' in the Asteroid Belt

The asteroid belt that exists between the orbits of Mars and Jupiter may also be a comet graveyard and some of the dead comets circling the Sun have the potential to become reignited after millions of years of inactivity, according to observations from astronomers at University of Anitoquia in Medellin, Colombia.

More than 1 million objects ranging from just a meter in size to more than 800 meters are present in the asteroid belt, the researchers say, and within the last decade 12 active comets have been found in the asteroid belt. The origins of these comets are intriguing for astronomers because they appear dissimilar to the standard, highly elliptical long-orbit comets that may only orbit the Sun once in a thousand or more years.

As these dead comets orbit around the Sun, the researchers contend that gravitational forces from other orbiting bodies, such a Jupiter, can occasionally cause the dormant comets to dip close enough to the Sun to become rekindled.

"We found a graveyard of comets," said astronomer Ignacio Ferrin. "Imagine all these asteroids going around the Sun for eons, with no hint of activity. We have found that some of these are not dead rocks after all, but are dormant comets that may yet come back to life if the energy that they receive from the Sun increases by a few percent."

The astronomers named the reborn comets after a historical figure with his own resurrection story, calling the space rocks "Lazarus comets."

The astronomers' finding creates room for a new interpretation of what the the asteroid belt was like eons ago. They suggest that it was once populated with thousands of active comets and that the 12 active comets observed in the belt today have come back to life after being extinguished for millennia.

"These objects are the 'Lazarus comets,' returning to life after being dormant for thousands or even millions of years," Ferrín explained. "Potentially any one of the many thousands of their quiet neighbors could do the same thing."