A new study by University of Maryland astronomers shows that comet Bernardinelli-Bernstein (BB), the largest comet ever discovered, was active long before previously thought, meaning the ice within it is vaporizing and forming an envelope of dust and vapor known as a coma. Only one active comet has been observed farther from the sun, and it was much smaller than comet BB.
Click here for original story, New study shows the largest comet ever observed was active at near-record distance
Source: Phys.org