The massive volcanic "devil comet," that is racing toward the sun may have lost the distinctive horns that earned it its sinister nickname. Last week, after the comet's latest and most violent outburst yet, its trademark head spikes did not appear as they did after previous eruptions. But astronomers have spotted several new characteristics of the comet, including a rare green hue and a mysterious "shadow."
Comet 12P/Pons-Brooks (12P), is a massive 10.5-mile-wide (17 kilometer) comet that is on course to make its closest approach to Earth for more than 70 years next summer. Comet 12P is a cryovolcanic, or cold volcano, comet that consists of an icy shell, or nucleus, filled with ice and gas. When the comet soaks up enough of the sun's radiation, its frosty innards, or cryomagma, get superheated. Pressure builds up within the nucleus until the shell cracks and the comet's icy guts spray into space. After an eruption, the comet's coma — a fuzzy, reflective cloud of cryomagma and dust — expands and makes the comet appear much brighter to astronomers as it reflects the sun's rays.
