Comet Bernardinelli-Bernstein – named after its discoverers – had been known since 2014, and astronomers had known since last year that it was a size “colossal”. But it took the help of the Hubble Space Telescope to determine the exact dimensions of this interstellar monster. The results, published this week and taken up by the New York Timesdid not disappoint.
“The comet’s nucleus could have a diameter of up to 137 kilometers” and its mass of 500,000 billion tons “equals about 2,800 Mount Everest”, specifies the New York daily. In total, Bernardinelli-Bernstein is 40% larger than its first runner-up, responding to the pretty name of C/2002 VQ94.
Despite its large size, this ball of ice with a hair of millions of miles – and a core “blacker than coal” – will only be visible to the naked eye from Earth in 2031, the scientists say. The comet, which is currently heading towards the sun at a speed of more than 35,000 km/h, will then reach the outskirts of Saturn, before turning around to set off again towards the depths of the solar system.
“Other secrets of the comet will be revealed as it approaches Saturn’s orbit” in 2031, but astronomers will know little more about its exact provenance, observes the New York Times.
Nevertheless, despite the lack of evidence, everything suggests that the comet comes from the mysterious cloud of Oort, “a hypothetical and as yet unobservable bubble, located around the solar system, and filled with primitive ice shards of various sizes and shapes”.
The comet could offer “a welcome glimpse of what lies in this bubble”according to David Jewitt, an astronomer at the University of California, Los Angeles (UCLA) and author of the latest Bernardinelli-Bernstein study.
There is in the region of the Oort cloud “a large number of objects that we have never seen, and an immense number of things that we do not even imagine”he says. “What the hell is going on over there? ”