CNN Indonesia
Sunday, 26 Nov 2023 17:34 IWST
Illustration. Experts explain why comets turn green. (via REUTERS/DAN BARTLETT)
Jakarta, CNN Indonesia —
The most powerful eruption of comet 12P/Pons-Brooks cryovolcanics suggests the icy object may have lost horns iconic, which earned him the nickname ‘the devil’s comet’, forever.
The eruption of a giant volcanic comet that was speeding towards the Sun occurred last week. As well as causing it to lose its antlers, the eruption was tracked to trigger a rare green color and a mysterious ‘shadow’.
Comet 12P/Pons-Brooks (12P), quoted from LiveScienceis a giant 10.5-mile-wide (17-kilometer) comet that will make its closest approach to Earth in more than 70 years next year.
This comet is a cryovolcanic comet, or cold volcano, consisting of an icy shell, or core, filled with ice and gas. When a comet absorbs enough solar radiation, the comet’s frozen interior, or cryomagma, becomes very hot.
Pressure builds inside the core until the shell cracks and the comet’s icy contents gush out into space.
After the eruption, the comet’s coma (an obscure, reflective cloud of cryomagma and dust) expands and makes the comet appear brighter to astronomers because it reflects sunlight.
Prior to this, 12P experienced three major eruptions: on July 20, when it was seen exploding for the first time in 69 years; on October 5, when the eruption was even more powerful; and on Halloween (October 31), where the explosions are less intense.
Each time the comet blows off its top, the coma expands into an irregular shape with “dark streaks” that make it look like it grows a pair of horns.
On November 14, 12P experienced another major eruption, the most extreme eruption so far.
Astronomers witnessed the comet temporarily become 100 times brighter than usual in the following days as its coma expanded, quoted from Spaceweather.com. But this time, the distinctive horns were no longer visible.
“The coma this time looks perfectly circular,” said Nick James, director of the British Astronomical Association’s (BAA) comet section.
The origin of the horn
Comet horns are the result of irregularities in the shape of the 12P nucleus, said BAA astronomer Richard Miles. According to him, the gas that escapes may be partly blocked by a prominent indentation in the core.
It is currently unclear why the horn disappeared. However, frequent eruptions may have destroyed notches that blocked cryomagma outflow.
During the third eruption on Halloween, the horn was less pronounced than in the first two eruptions, indicating that the notch may have been damaged after the comet’s first two explosions.
Amateur astronomer and photographer Eliot Herman, who has taken photos of the comet every day since its first eruption, said he was surprised when the coma expanded without growing horns.
“The devil may be gone [untuk selamanya],” she said.
The image taken by Herman also revealed another surprise, namely the green color of the comatose comet.
This rare coloring is produced by comets containing high levels of dicarbon, a chemical that emits a green light when decomposed by sunlight, according to the magazine Science.
Several green comets have flyby Earth this year, including “green comet” C/2022 E3 (ZTF), which reached its closest approach to Earth in 50 thousand years in February; and Comet Nishimura, which flew by our planet for the first time in 430 years in September.
In follow-up images of the comet, Herman also saw other strange dark spots in the comet’s colorful coma, which looked like curved gaps.
However, unlike the misshapen dark trails that previously characterized comas, experts believe that this unusual shape is a shadow cast by escaping cryomagma, according to Spaceweather.com.
12P is currently hurtling toward the sun at about 40,000 miles per hour (64,300 km per hour) as it nears the end of its 71-year orbit around the sun.
On April 24, 2024, the comet will reach its closest point to the Sun, or perihelion, before being flung around our home star and into the outer solar system where it will spend most of its orbit.
Most likely, it will not return to the inner solar system until 2094. 12P will reach its closest point to Earth on June 2 next year and is expected to be visible to the naked eye.
(rfi/arh)
2023-11-26 10:34:01
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