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Hubble Space Telescope Confirms Largest Comet Nucleus Ever Seen

NASA's Hubble Space Telescope has confirmed the magnitude of the biggest comet nucleus ever seen by scientists.

The Hubble Space Telescope of NASA has measured the size of the biggest ice comet nucleus ever seen by scientists. It has an estimated diameter of 80 miles, making it larger than the state of Rhode Island. The nucleus is almost 50 times bigger than the nucleus of most known comets. Its mass is predicted to be 500 trillion tonnes, a hundred thousand times that of a normal comet discovered far closer to the Sun.

Image credits: Illustration: NASA, ESA, Zena Levy (STScI)

The size of the frozen, solid nucleus of comet C/2014 UN271 (Bernardinelli-Bernstein) is compared to that of numerous other comets in this graphic. The bulk of detected comet nuclei are smaller than Halley's comet. They are usually a mile or less across. Comet C/2014 UN271 now holds the record for large comets. And it's possible that this is simply the top of the iceberg. As sky surveys increase in sensitivity, astronomers may find many more monsters to name. Though scientists know this comet must be large to have been seen so far away from Earth, only the Hubble Space Telescope has the sharpness and sensitivity to provide a definitive estimate of nucleus size.

The gigantic comet C/2014 UN271 (Bernardinelli-Bernstein) is barreling through the solar system at 22,000 miles per hour. But don't worry. It will never go closer to the Sun than 1 billion miles, which is somewhat farther than Saturn's distance. And it won't happen until 2031.

Comet C/2002 VQ94 held the previous record, with a nucleus estimated to measure 60 miles large. The Lincoln Near-Earth Asteroid Research (LINEAR) project detected it in 2002.

This comet is basically just the tip of the iceberg when it comes to the many thousands of comets that are located in the more remote regions of the solar system and are too blurry for humans to see "Professor of planetary science and astronomy at the University of California, Los Angeles (UCLA) David Jewitt, who is also a co-author of the new study that was recently published in The Astrophysical Journal Letters, commented on the findings. "Since it shines with such a strong light from such a wide distance, we have always presumed that this comet must be rather large because of how far away it is. At this point, we are able to confirm that it is.

Credits: NASA, ESA, Man-To Hui (Macau University of Science and Technology), David Jewitt (UCLA); Image processing: Alyssa Pagan (STScI)

Comet C/2014 UN271 was identified in archival pictures from the Dark Energy Survey at Chile's Cerro Tololo Inter-American Observatory by astronomers Pedro Bernardinelli and Gary Bernstein. It was discovered by chance in November 2010, when it was 3 billion miles from the Sun, about the usual distance to Neptune. It has been extensively investigated since then by land and space-based telescopes.

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The difficulty in measuring this comet was distinguishing the solid core from the massive dusty coma around it. Hubble can't see the nucleus of the comet right now because it's too far away. The Hubble measurements, on the other hand, reveal a sharp spike of light near the nucleus' position. Hui and his colleagues then created a computer model of the surrounding coma, which they tweaked to suit the Hubble photos. The coma's light was then removed to reveal the starlike core.

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"At 22,000 miles per hour, the gigantic comet is barreling this way from the boundary of the solar system," NASA announced on its official website.

"Don't worry: the comet will still pass closer to the Earth than Saturn," NASA tweeted.

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