79-Hubble Confirms Largest Comet Nucleus Ever Seen

This diagram compares the size of the icy, solid nucleus of comet C/2014 UN271 (Bernardinelli-Bernstein) to several other comets. The majority of comet nuclei observed are smaller than Halley’s comet. They are typically a mile across or less. Comet C/2014 UN271 is currently the record-holder for big comets.

NASA’s Hubble Space Telescope has determined the size of the largest icy comet nucleus ever found. And, it’s big! With a diameter of approximately 80 miles across, it’s about 50 times larger than typical comets. Its 500-trillion-ton mass is a hundred thousand times greater than the average comet.