Seven years ago, a pair of astronomers analysing high-resolution space photos discovered short glimpses of a bright round object poking out from a massive cloud of icy objects more than 2 billion miles from Earth.
The object resembled a massive comet. It was the most giant comet ever seen, estimated to be between 60 and 100 miles wide. And it appears to be heading towards Earth.
The giant object’s discoverers, University of Pennsylvania astronomers Gary Bernstein and Pedro Bernardinelli, verified their suspicions last month after combining their prior data with new sightings of the distant object.
The researchers named it the Bernardinelli-Bernstein (BB) comet. They called it the “nearly spherical cow of comets” in their paper, submitted for publication in The Astrophysical Journal Letters on Sept. 23.
The most alarming aspect is that the comet is on its way back to Earth, on a course that began billions of years ago during the original cosmic events that created our planet. According to the two astronomers, the comet’s track will swing between Uranus and Saturn in 2031.
The Bernardinelli-Bernstein comet is an extremely unusual and one-of-a-kind prize for any scientist attempting to piece together the history of the solar system. “In essence, it’s a time machine,” said Amy Mainzer, an astronomer and comet expert at the University of Arizona.
The comet’s journey is the opportunity of a lifetime for scientists anxious to learn about the conditions and building blocks of the solar system that one day led to Earth and all its life.
“It’s pristine,” Bernardinelli said. “Not a lot has happened to this object since its formation in the early days of the solar system, and so we can think of it as a window into the past.”