Hubble Finds Comet With the Largest Nucleus

Scientists are all eyes on the behemoth comet, C/2014 UN271 (Bernardinelli-Bernstein). NASA's Hubble Space Telescope has determined that the nucleus of this comet is the largest ever found. The estimated diameter of this comet's nucleus is approximately 80 miles across. According to astronomers, the nucleus is almost 50 times bigger than found in most known comets. Scientists estimate that the mass of this comet's nucleus is around 500 trillion tons. That is a hundred thousand times more than the mass of a typical comet found much closer to the Sun.

Comet C/2014 UN271 is currently moving towards the edge of the solar system at a staggering speed of 22,000 miles per hour. Even when it's closest to the Sun, it will be one billion miles away from the star. And, this is not supposed to happen any time before 2031.

The new study was published in The Astrophysical Journal Letters.

David Jewitt, a professor of planetary science and astronomy at the University of California, Los Angeles (UCLA), and co-author of the new study, said in a statement, “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.”

He added, “We've always suspected this comet had to be big because it is so bright at such a large distance. Now we confirm it is.”

Astronomers Pedro Bernardinelli and Gary Bernstein discovered the comet C/2014 UN271 in archival images from the Dark Energy Survey at the Cerro Tololo Inter-American Observatory in Chile

The paper's lead author Man-To Hui of the Macau University of Science and Technology, Taipa, Macau, said, “We guessed the comet might be pretty big, but we needed the best data to confirm this.”

Hui and his team studied the brightness of the comet nucleus from radio observations from the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile. The team compared it with the new Hubble measurements. They found the Hubble measurements were close to the estimates from ALMA. But they found it to be bigger and darker.

While measuring this comet, scientists faced the challenge of discriminating the solid nucleus from the huge dusty coma enveloping it.