Even though NASA also focuses on asteroid threats, new research recommends that they have to also look just beyond the orbit of Jupiter, where the distant comets lie in wait. We know that a comet strike may have wiped out the dinosaurs, and another incident like that would mean major destruction for Earth. Hundreds of these huge comets, called 'centaurs,' have been found in past 20 years. Centaurs are essentially balls of ice and dust, but the actual threat is their unstable orbit that starts just beyond Neptune. They can be 31 to 61 miles wide. A single centaur comprises more mass than the whole population of Earth-crossing asteroids discovered to date. Their unstable orbit let them zip pass quite closely to the orbit of Jupiter, Saturn, Uranus, and Neptune.
Orbit of hundreds of comets, called 'centaurs,'
The researchers reason that concentrating on near-Earth asteroids undervalues the nature and scale of potential giant comet strikes.
Co-author Bill Napier of the University of Buckingham said “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,”
He continued “Our work suggests we need to look beyond our immediate neighborhood too, and look out beyond the orbit of Jupiter to find centaurs. If we are right, then these distant comets could be a serious hazard, and it's time to understand them better.”
In their research paper the researchers wrote “'A centaur arrival carries the risk of injecting, into the atmosphere…a mass of dust and smoke comparable to that assumed in the nuclear winter studies”
NASA tracks almost 12,992 near-Earth objects which have been revealed orbiting inside our solar system close to our own orbit. It approximates about 1,607 are categorized as Potentially Hazardous Asteroids.
The up-to-date study suggests several hundred more Centaurs must be added to the list of space rocks that pose serious threat to Earth.