A new study suggests that the search for and tracking of Potentially Hazardous Asteroids should probably take a back seat to finding and tracking massive comets that could pose a serious threat to the Earth. Given that there are hundreds of these giant objects, called “centaurs,” that have recently been discovered among the outer planets of the Solar System, knowing where they are and where they are headed might prove advantageous for our planet’s survival.
Space.com reported December 28 that it was the discovery of this large population of centaurs that prompted a group of scientists to “re-assess the threat of these seemingly distant bodies to this planet.” What the group found was that at least one massive comet — or a shower of its disintegrating body — collides with Earth once every 40,000 to 100,000 years. The cometary impact — or at least its debris trail — could trigger significant environmental upheaval and could possibly have been responsible for the catastrophic die-off of the dinosaurs some 65 million years ago.
There are several reasons scientists believe the centaurs might pose a greater threat to Earth than asteroids. There is the possibility that there are far more of them than currently accounted for, especially since many comets are believed to originate far beyond Pluto in the outer reaches of the Solar System in the Oort Cloud. Of those observed among the outer planets,the average size of the objects range from 31 to 62 miles in diameter, sizes that could easily destroy life as it exists on Earth — or at least significantly disrupt current ecological conditions.
“In the last three decades, we have invested a lot of effort in tracking and analyzing the risk of a collision between the Earth and an asteroid,” said Bill Napier, an honorary professor in the Centre for Astrobiology at the University of Buckingham in the United Kingdom, in the statement. (Some of that research is embodied in NASA’s growing database on Near Earth objects, a catalog of asteroids being monitored called, appropriately enough, the Near Earth Object Program.) Napier says that we must look farther out into the Solar System. “If we are right, then these distant comets could be a serious hazard, and it’s time to understand them better.”
In the statement, Napier also explained how centaurs likely disrupted life on Earth even far more recently than when the dinosaurs began their decline toward extinction. He said that a centaur probably entered the Earth’s relative neighborhood about 30,000 years ago (concluded from the study of the ages of Moon rocks and craters on the Moon). Other environmental disruptions on Earth in 10,000 B.C. and 2,300 B.C. may have occurred due to centaurs as well, Napier noted.
The new study and analyses is just the latest in suggesting that life on Earth has been in some ways impacted by objects from the outer Solar System. In late October, lauded Harvard physicist Lisa Randall released her latest book, Dark Matter and the Dinosaurs: The Astounding Interconnectedness of the Universe, which suggested that the evolution of humans could very well be the consequence of a large meteor, which became the famed Chixhulub meteor that wiped out the dinosaurs, which was ultimately sent Earth’s way due to a periodic disruption caused by the Solar System’s interaction with dark matter.