New study shows the largest comet ever observed was active at near-record distance

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.