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NASA's Hubble Space Telescope has determined the size of the largest icy comet nucleus ever seen by astronomers. The estimated diameter is approximately 80 miles across, making it larger than the state of Rhode Island. The nucleus is about 50 times larger than found at the heart of most known comets. Its mass is estimated to be a staggering 500 trillion tons, a hundred thousand times greater than the mass of a typical comet found much closer to the Sun. The behemoth comet, C/2014 UN271 (Bernardinelli-Bernstein) is barreling this way at 22,000 miles per hour from the edge of the...

Artist's impression of C/2014 UN271 (Bernardinelli-Bernstein). (NOIRLab/NSF/AURA/J. da Silva/Spaceengine) ====================================================================================== A comet so huge it was initially mistaken for a dwarf planet is on an inward-bound trajectory from the outer Solar System. There's no reason to worry – C/2014 UN271 (Bernardinelli-Bernstein), as the comet is called, will approach no closer to the Sun than just outside the orbit of Saturn. But its large size and relative closeness will afford a rare opportunity to study a pristine object from the Oort Cloud, and find new information about the formation of the Solar System. "We have the privilege of having discovered perhaps...

Of the 461 objects described for the first time in the new paper, a few stand out. Nine are known as extreme trans-Neptunian objects, which have orbits that swing out at least 150 AUs from the sun. Four of those are extremely extreme, with orbital distances of 230 AUs. At these distances, the objects are hardly affected by Neptune's gravity, but their strange orbits suggest an influence from outside the solar system. Some researchers think that influence might be a yet-undiscovered planet, dubbed Planet Nine. (Others think that the combined gravity of lots of little objects, or, alternatively, nothing more...

Scientists briefly estimated that Comet Bernardinelli-Bernstein, as it's now known, was the largest such icy body identified to date, perhaps more than 100 miles (160 kilometers) across. Additional observations have cast that into doubt, but given the "megacomet" a new distinction: it sprouted a tail remarkably far from the sun, suggesting more revelations to come. All told, the object offers astronomers an unprecedented opportunity to watch the antics of a comet. Although what initially stood out to Bernardinelli was the comet's weird orbital characteristics, the discovery made such a splash because of a different trait, the comet's estimated size. Based...

A comet unlike any other in recorded history is on a trajectory to zip through the inner solar system in less than a decade, but like most space rocks that make the news, it isn’t anything to lose sleep over. Comet 2014 UN271 was observed during a mission called the Dark Energy Survey back in 2014, but skywatchers didn’t realize that the data gathered was showing a comet until mid-June of this year. Pedro Bernardelli and Gary Bernstein were the two people who made this realization, giving Comet 2014 UN271 a name that rolls off the tongue a bit easier:...