French astronomers confirm the existence of the largest comet in history

Scientists from the Paris Observatory and the Institute of Astrophysics of Andalusia (CSIC) establishedSize and albedo of the largest detected Oort-cloud object: comet C/2014 UN 271 (Bernardinelli-Bernstein) / Cornell Universitythat comet Bernardinelli-Bernstein (object C/2014 UN271) from the Oort Cloud is the largest comet on record. It broke the record for Comet Hale-Bopp (C/1995 O1), which previously topped the list.

Astronomers Pedro Bernardinelli and Gary Bernstein discovered comet C/2014 UN271 in 2014 while searching for dark energy in the solar system. Researchers later determined that the object came from the Oort Cloud. This is a hypothetical region in the solar system that is spherical and possibly the source of long-period comets - which take 200 years or more to orbit the sun.

When the comet Bernardinelli-Bernstein was first noticed, it was about the same distance from the Earth as Neptune - about 4 billion km. Then scientists assumed that its diameter could be from 100 to 370 km, but more accurate data could not be obtained.

Some astrophysicists even believed that C/2014 UN271 was not a comet, but a minor planet. This term is not included in the official classification, but is often used for celestial bodies whose dimensions are lie between planets and comets, e.g. for asteroids, dwarf planets, centaurs, Trojan satellites.

New information from the Atacama Large Millimeter Array, a radio telescope complex in the Chilean desert, has made it possible to refine the size of the comet. According to the wavelength of light that was reflected from the body, scientists calculated its diameter - 137 km. The diameter of comet Hale-Bopp, which was previously considered the largest in history, is almost half that - 74 km.

The scientists also noted that the determination of the size of comet Bernardinelli-Bernstein was the farthest measurement of the comet's albedo (reflectivity) ever observed. The technique used will make it possible to monitor the reduction in the diameter of the comet due to the melting of ice as it approaches the Sun. On the way back, it can become half as much.