Although comets are more recognizable for their flow tails, which can stretch for millions of kilometers, a comet’s heart is its solid core. This core is made of ice and dust, which forms a dirty snowball. While most of the known comet nuclei are a few kilometers in diameter, astronomers using the Hubble Space Telescope have located Comet C / 2014 UN271 with a nucleus that reaches 136 kilometers (85 miles) in diameter. That’s more than twice the width of Rhode Island. This nucleus is about 50 times larger than those of other comets and has an estimated mass of 500 trillion tons, which is 100,000 times the mass of a typical comet. The comet is moving at 35,400 kilometers (22,000 miles) per hour from the edge of our solar system and will make its closest approach in 2031. But it will never approach more than 1.6 billion kilometers (one billion miles) away from the sun – a little further from the distance between Earth and Saturn. The comet was discovered by astronomers Pedro Bernardinelli and Gary Bernstein as they examined archival images taken by the Dark Energy Survey at the Cerro Tololo Observatory in Chile. The comet was first observed in 2010 and is also known as the Bernardinelli-Bernstein comet in honor of its discoveries. Since then, astronomers have observed the comet with ground-based and space-based telescopes. In January, researchers used the Hubble Space Telescope to take five photos of the comet. The images are part of a new study published Tuesday in The Astrophysical Journal Letters. “This comet is literally the tip of the iceberg for the many thousands of comets that are too dim to see in the most remote parts of the solar system,” said study co-author David Jewitt, a professor of planetary science and astronomy at the University of California. , Los Angeles, in a statement. “We always suspected that this comet had to be big because it is so bright at such a distance. Now we confirm that it is.” Comets are remnants of the first days of the solar system, frozen pieces left over from the moment the planets formed. The gravity of the largest planets sent comets into the Oort Cloud and the cloud is now home to distant comets on the edge of our deep-space solar system. Comets travel back to the sun when their orbits experience the gravitational pull of passing stars. In a few million years, Comet Bernardinelli-Bernstein will orbit him back in the Oort Cloud. “This is an amazing object, given how active it is when it is still so far from the Sun,” lead author Man-To Hui, an assistant professor at Macau University of Science and Technology in Taipei, Macao, said in a statement. “We guessed the comet might be big enough, but we needed the best data to confirm it.” The team used Hubble data to distinguish the comet’s nucleus from the coma or dusty shell surrounding a comet as it gets closer to the sun. The sun’s heat heats the comet as it approaches, causing parts of it to sublimate or transition from solid to gas. This cloudy coma is why comets look blurry when viewed through telescopes. The team analysis not only revealed the size of the nucleus, but also the fact that it is darker than carbon, Jewitt said. The comet is experiencing an orbit of 3 million years, oval in shape. It is now less than two billion miles from our sun. Astronomers hope that the study of Comet Bernardinelli-Bernstein could reveal more about the Oort Cloud, first hypothesized by Dutch astronomer Jan Oort in 1950. The cloud remains a theory because it is too far to observe, so the larger structure in our solar system is virtually invisible. NASA’s Voyager spacecraft will not reach the inner Oort cloud for another 300 years – and it may take 30,000 years to pass through it. But every comet that approaches the sun reveals more details about their mysterious home.
