NASA Spots The Largest Icy Comet Ever And It's Barreling Towards Earth At 22K MPH

comet sizes
NASA's Hubble Space Telescope has confirmed the largest icy comet nucleus ever detected by astronomers. The comet's nucleus is larger than the state of Rhode Island, to put its size into perspective.

The gargantuan comet, C/2014 UN271 (Bernardinelli-Bernstein) has a nucleus that is approximately 50 times larger than other known comets and has a mass that is estimated to be an astounding 500 trillion tons. This means it has a mass a hundred thousand times greater than the mass of a typical comet found closer to the Sun.

A recent Twitter post by NASA Hubble said the comet is traveling at a breakneck speed of 22,000 miles per hour. It's also headed in our general direction, but no need to sound the alarm—it will never get closer than 1 billion miles away from the Sun, or a distance slightly farther than Saturn. Previously the record was held by comet C/2022 VQ94, which has a nucleus estimated to be about 60 miles across.

"This comet is literally the tip of the iceberg for many thousands of comets that are too faint to see in the more distant parts of the solar system," said David Jewitt, a Professor of Planetary Science and Astronomy at the University of California, Los Angeles, and co-author of the new study in The Astrophysical Journal Letters. "We've always suspected this comet had to be big because it is so bright at such a large distance. Now we can confirm it."

It was first discovered by accident in 2010 by astronomers Gary Bernstein and Pedro Bernadinelli in archival images from the Dark Energy Survey at the Cerro Tololo Inter-American Observatory in Chile. At the time it was observed, it was a massive 3 billion miles from the Sun, or around the same distance as Neptune.

"This is an amazing object, given how active it is when it's still so far from the Sun," indicated the paper's lead author Man-To Hui of the Macau University of Science and Technology, Taipa, Macau. "We guessed the comet might be pretty big, but we needed the best data to confirm this," which led the team to utilize Hubble to take five images of the comet on January 8, 2022.

hubble comet
Image Credit: NASA

The team was first challenged with having to discriminate the solid nucleus from the large dusty coma surrounding it. They were able to do this by first creating a model of the coma by fitting the surface brightness profile assembled from the original observation. This allowed researchers to subtract the coma and reveal the point-like glow from the nucleus. At this point, the team was able to combine the image with radio telescope data and deduct a precise measurement of the nucleus size.

Comet C/2014 UN271 is believed to have originated from the Oort Cloud, which is a hypothesized nesting ground of trillions of comets. It is believed that the Oort Cloud did not actually form so far from the Sun, but rather was bounced out of the solar system billions of years ago by a gravitational "pinball game" among the much larger outer planets. Researchers believe the comet has been hurtling toward the Sun for well over 1 million years.