Hubble Comet C/2014 UN271 Nucleus (IMAGE) NASA/Goddard Space Flight Center Caption This sequence shows how the nucleus of Comet C/2014 UN271 (Bernardinelli-Bernstein) was isolated from a vast shell of dust and gas surrounding the solid icy nucleus. On the left is a photo of the comet taken by the NASA Hubble Space Telescope's Wide Field Camera 3 on January 8, 2022. A model of the coma (middle panel) was obtained by means of fitting the surface brightness profile assembled from the observed image on the left. This allowed for the coma to be subtracted, unveiling the point-like glow from the nucleus. Combined with radio telescope data, astronomers arrived at a precise measurement of the nucleus size. That's no small feat from something about 2 billion miles away. Though the nucleus is estimated to be as large as 85 miles across, it is so far away it cannot be resolved by Hubble. Its size is derived from its reflectivity as measured by Hubble. The nucleus is estimated to be as black as charcoal. The nucleus area is gleaned from radio observations. Credit NASA, ESA, Man-To Hui (Macau University of Science and Technology), David Jewitt (UCLA) Image Processing: Alyssa Pagan (STScI) Usage Restrictions No restrictions. License Public Domain Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.