Astronomers confirm the size of the largest comet ever discovered larger than Rhode Island

4 billion year old relics from the early solar system on their way to us

Diagram comparing the size of the icy, solid core of comet C / 2014 UN271 (Bernardinelli-Bernstein) with several other comets. Credit: NASA, ESA, Zena Levy (STScI)

Astronomers using NASA’s Hubble Space Telescope have confirmed the existence of the largest comet ever discovered, and it will pass our Sun in the next decade.

Comets differ from asteroids in that asteroids are rocky objects, while as a comet is a sphere of ice and dust. Comets are also known for the “tail” they leave behind and the glowing head, or nucleus, that appears as it approaches the sun.

Now astronomers have determined the size of “the largest ice-cold comet nucleus ever seen.” Comet C / 2014 UN271, also known as Comet Bernardinelli-Bernstein, is about 80 miles wide, larger than Rhode Island. Its core is estimated to weigh 500 trillion tons, about 100,000 times larger than most comets.

Also, the comet travels at 22,000 mph and is heading closer to Earth. It will not be worrying when it gets closest in 2031, because it will be about 1 billion miles away from the sun, slightly longer than the distance between Earth and Saturn. The findings about the comet were published Tuesday in the journal The Astrophysical Journal Letters.

“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, professor of planetary science and astronomy at UCLA and co-author of the study. said in a statement. “We’ve always suspected that this comet was going to be big because it’s so bright at such a great distance. Now we’re confirming that it is.”

First discovered by astronomers Pedro Bernardinelli and Gary Bernstein in stock images in 2014, the comet was discovered when it was more than 3 billion miles from the sun, an indicator of its size.

“We guessed the comet could be quite large, but we needed the best data to confirm this,” said Man-To Hui of the Macau University of Science and Technology in Taipa, Macau, and lead author of the study.

To confirm the size of the comet, astronomers took pictures of it using the Hubble Telescope on January 8. But the challenge of interpreting the images was to distinguish the core of the comet from the cloud and tail, or the coma that surrounds it. As a comet gets closer to the sun, it heats up and the coma expands.

The comet is about 2 billion miles away from the sun, where the temperature is estimated minus 348 degrees Fahrenheit, but enough for carbon monoxide to sublimate from the comet’s surface to form a coma.

Hui and colleagues then made a computer model of the comet and adapted it to the telescope images. They were then able to remove the coma to leave only the nucleus.

Hui and his colleagues then made a computer model of the surrounding coma and adjusted it to fit the Hubble images. Then they pulled the glow from the coma off.

The team then took the core images and compared its brightness with radio observations from the Atacama Large Millimeter / Submillimeter Array (ALMA) in Chile. The combined data allowed astronomers to determine its diameter, as well as what the nucleus actually looks like.

“It’s big and it’s more black than coal,” Jewitt said.

It takes the comet 3 million years to orbit the solar system, and it reaches as far as half a light-year from the sun.

Astronomers hope the comet will provide answers to what comets from the Oort cloud are like. The Oort cloud is thought to be a massive nesting site for trillions of comets; it has not yet been observed directly.


4 billion year old relics from the early solar system on their way to us


More information:
Man-To Hui et al., Hubble Space Telescope Detection of Comet Core C / 2014 UN271 (Bernardinelli – Bernstein), The Astrophysical Journal Letters (2022). DOI: 10.3847 / 2041-8213 / ac626a

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