City-size comet racing toward Earth regrows 'horns' after massive volcanic eruption
The cryovolcanic comet 12P/PonsâBrooks, which will make its closest approach to Earth next year, has re-sprouted its distinctive "horns" after its second major eruption in four months.
An enormous volcanic comet the size of a small city has violently exploded for the second time in four months as it hurtles toward the sun. And just like the previous eruption, the cloud of ice and gas emitted what looked like a gigantic pair of horns.
The comet, named 12P/Pons-Brooks, is a cryovolcanic â or cold volcano â comet. It has a solid nucleus, with an estimated diameter of 18.6 miles (30 kilometers), and is filled with a mix of ice, dust and gas known as cryomagma. The nucleus is surrounded by a fuzzy cloud of gas called a coma, which leaks out of the comet's interior.
When solar radiation heats the comet's insides, the pressure builds up and the comet violently explodes, shooting its frosty guts out into space through large cracks in the nucleus's shell.
On Oct. 5, astronomers detected a large outburst from 12P, after the comet became dozens of times brighter due to the extra light reflecting from its expanded coma, according to the British Astronomical Association (BAA), which has been closely monitoring the comet
Over the next few days, the comet's coma expanded further and developed its "peculiar horns," Spaceweather.com reported. Some experts joked that the irregular shape of the coma also makes the comet look like a science fiction spaceship, such as the Millennium Falcon from Star Wars.
The unusual shape of the comet's coma is likely due to an irregularity in the shape of 12P's nucleus, Richard Miles, a BAA astronomer, told Live Science after the comet's previous eruption. The outflowing gas is likely being partially obstructed by a notch sticking out on the nucleus, Miles said. As the gas continues to expand away from the comet, the irregularity in the coma's shape becomes more defined and noticeable, he added.
12P is currently hurtling toward the inner solar system, where it will be slingshotted around the sun on its highly elliptical 71-year orbit around our home star â similar to the green comet Nishimura, which pulled off a near-identical maneuver on Sept. 17.
12P will reach its closest point to Earth on April 21, 2024, when it may become visible to the naked eye before being catapulted back toward the outer solar system. It will not return until 2095.
This is the second time 12P has sprouted its horns this year. On July 20, astronomers witnessed the comet blow its top for the first time in 69 years (mainly due to its outbursts being less frequent and harder to spot during the rest of its orbit). On that occasion, 12P's coma grew to around 143,000 miles (230,000 km), which is around 7,000 times wider than the comet's nucleus.
It is unclear how large the coma grew during the most recent eruption, but there are signs the outburst was "twice as intense" as the previous one, the BAA noted. By now, the coma has likely shrunk back to near its normal size.
As 12P continues to race toward the sun, there is a high probability that we will witness several more major eruptions. It is possible that those eruptions will be even bigger than the most recent one as the comet soaks up more solar radiation, according to Spaceweather.com.
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But 12P is not the only volcanic comet that astronomers are currently monitoring: 29P/Schwassmann-Wachmann (29P) â the most volatile volcanic comet in the solar system â has also had several noticeable eruptions in the last year.
In December 2022, 29P experienced its largest eruption in around 12 years, which sprayed around 1 million tons of cryomagma into space. And in April this year, for the first time ever, scientists accurately predicted one of 29P's eruptions before it actually happened, thanks to a slight increase in the comet's brightness in the lead-up to the icy explosion.
The British Astronomical Association (BAA) has been closely monitoring the intriguing celestial phenomenon known as Comet 12P/Pons-Brooks. This comet, which is approximately three times larger than Mount Everest, has recently caused a stir in the astronomical community by erupting for the second time in just four months, and it’s now hurtling on a trajectory that brings it closer to Earth.
Comet 12P is a cryovolcanic comet, characterized by its cold volcanic activity. With a colossal diameter of 18.6 miles (30 kilometers), it first erupted on October 5, marking its second eruption in the last four months, with the previous event occurring in July. The BAA noticed this recent explosion as the comet appeared significantly brighter due to the reflection of light by its coma, the gas cloud that surrounds its core.
In the days that followed, the comet’s coma expanded and developed what scientists have humorously described as “peculiar horns.” This unusual feature has led to comparisons with science fiction spaceships, like the Millennium Falcon from ‘Star Wars.’
The exact cause of these distinctive horns remains a mystery, but experts speculate they may be linked to the shape of 12P’s nucleus. Richard Miles of the British Astronomical Association suggested that the horns might result from a uniquely shaped cryovolcanic vent or some form of blockage that affects the way materials are expelled.
Despite its intriguing behavior, there is no need for Earth to prepare for a “deep impact” just yet. Scientists have reassured the public that the comet won’t come closest to Earth until 2024 when it will be visible to the naked eye. After this encounter, it will return to the depths of our solar system, not reappearing until the year 2095.
Comet 12P’s most recent eruption appears to have been even more intense than the previous one. While the exact size of the coma during this eruption is unclear, signs suggest that it was “twice as intense” as the earlier event. It’s expected that the coma has now returned to its typical size.
This comet has garnered significant attention due to its unusual behavior and characteristics. Discovered by Jean-Louis Pons in 1812, it is one of the approximately 20 known comets with active ice volcanoes, making it a fascinating subject of study for astronomers and space enthusiasts alike. As it continues to capture our imagination, scientists will remain vigilant in monitoring its cosmic journey in the years to come.
