The Oort-cloud comet C/2014 UN271 (Bernardinelli-Bernstein) is a remarkable discovery for three reasons: it was found inbound as far as 29 au from the Sun, showing cometary activity at 24 au, and has a nuclear magnitude indicating an exceptionally large object. The comet is expected to exhibit gas emissions as it approaches its 11 au perihelion in 2031. Using ALMA, researchers measured the comet’s continuum flux at 1287 um, detecting thermal emission attributed solely to the nucleus. With a diameter of 137 km and a unique albedo, C/2014 UN271 is confirmed as the largest Oort-cloud object and one of the largest comets in the Solar System.
https://arxiv.org/abs/2201.13188