The Comet Bernardinelli-Bernstein (BB), represented in this artist’s rendition as it might look in the outer Solar System, is estimated to be about 1000 times more massive than a typical comet. The largest comet discovered in modern times, it is among the most distant comets to be discovered with a coma, which means ice within the comet is vaporizing and forming an envelope of dust and vapor around the comet’s core. Credit: NOIRLab/NSF/AURA/J. da Silva
University of Maryland astronomers discovered that comet Bernardinelli-Bernstein is among the most distant active comets from the sun, providing key information about its composition.
The largest comet ever discovered became active much farther from the sun than previously believed, according to a new study by University of Maryland astronomers.
Only one other active comet—meaning one that has formed an envelope of dust and vapor known as a coma—has been observed farther from the sun; however, it was much smaller than comet Bernardinelli-Bernstein (BB), which at 100 km in diameter dwarfs every other known comet by a hefty margin. (Halley’s comet, by comparison, is 15 km in diameter, while 1 km is typical.)
The finding, which will help astronomers determine what BB is made of and provide insight into conditions that existed billions of years ago during the formation of our solar system, was published on November 29, 2021, in The Planetary Science Journal.
“These observations are pushing the distances for active comets dramatically farther than we have previously known,” said Tony Farnham, a research scientist in the UMD Department of Astronomy and the lead author of the study.
Often called “dirty snowballs” or “icy dirtballs,” comets are conglomerations of dust and ice left over from the solar system’s early days. How warm they must be to start vaporizing as their orbit carries them closer to the sun depends on what kind of ice they contain: water, carbon dioxide, carbon monoxide or some other frozen compound.
Scientists first discovered comet BB beyond the orbit of (function(d, s, id){
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