A peculiar volcanic comet hurtling toward the sun seemed to have "grown horns" from its explosion, which turned it into a tiny star and sent a shower of very cold "magma" into space. This comet is exploding for the first time in almost 70 years, according to observations.
This comet, known as 12P/Pons-Brooks (12P), is a cryovolcanic comet, or comet that is a cold volcano. The icy object, like all comets, consists of a solid nucleus that is packed with a mixture of gas, dust, and ice. A coma, or hazy cloud of gas, erupts from the comet's core and surrounds the nucleus. However, in contrast to the majority of comets, 12P's nucleus accumulates so much gas and ice that it has the ability to burst violently, ejecting its cryomagma—a frozen interior—through significant cracks in the nucleus's shell.
According to Spaceweather.com, on July 20, many astronomers saw a significant eruption from the comet, which abruptly became around 100 times brighter than it typically is. The comet's coma unexpectedly swelled up with gas and ice crystals released from the comet's interior, enabling it to reflect more sunlight back to Earth and cause an increase in brightness.
A photograph captured on July 24 at 12P (circled) The picture has poor quality, but the coma's horns are apparent. (Photo courtesy of The Dark Side Observatory and Thomas Wildoner)
Richard Miles, an astronomer with the British Astronomical Association who studies cryovolcanic comets, told Live Science via email that as of July 26, the comet's coma had grown to about 143,000 miles (230,000 kilometres) across, or more than 7,000 times wider than its nucleus, which has an estimated diameter of around 18.6 miles (30 km).
Interestingly, however, the comet seems to have developed horns due to an irregularity in the form of an extended coma. According to Spaceweather.com, other analysts have also drawn comparisons between the misshapen comet and the famous Star Wars spacecraft, the Millennium Falcon.
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According to Miles, there is probably a form irregularity in 12P's nucleus, which accounts for the comet's peculiar coma shape.
An out-sticking lobe on the nucleus most likely generated a "notch" in the enlarged coma, obstructing some of the outflowing gas. The notch, or "shadow," became more apparent as the gas grew and moved farther away from the comet, he said. But once the gas and ice are too scattered to reflect sunlight, the expanding coma will finally vanish.