C/2014 UN271 (Bernardinelli–Bernstein)
(Bernardinelli–Bernstein), simply known as or Comet Bernardinelli–Bernstein (nicknamed BB), is a large Oort cloud comet discovered by astronomers Pedro Bernardinelli and Gary Bernstein in archival images from the Dark Energy Survey. When first imaged in October 2014, the object was from the Sun, almost as far as Neptune's orbit and the greatest distance at which a comet has been discovered. With a nucleus diameter of at least , it is the largest Oort cloud comet known. It is approaching the Sun and will reach its perihelion of 10.9 AU (just outside of Saturn's orbit) in January 2031. It will not be visible to the naked eye because it will not enter the inner Solar System. Observational history Discovery was discovered by astronomers Pedro Bernardinelli and Gary Bernstein in an algorithm-assisted search for slowly-moving trans-Neptunian objects, in archival images from the Dark Energy Survey (DES) at Cerro Tololo Inter-American Observatory. It was detected at the 22nd apparent magnitude in 42 DES images spanning 10 October 2014 to 26 November 2018. The long observation arc by the DES images revealed that the object was on a near-parabolic trajectory inbound towards the Solar System, implying a cometary origin from the Oort cloud, despite