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A bizarre, volcanic comet has erupted violently, hurling more than 1 million tons of gas, ice and the “potential building blocks of life” into Earth solar system.
Known as 29P/Schwassmann-Wachmann (29P), the fleeting comet is about 37 miles (60 kilometers) wide and takes about 14.9 years to orbit Sun. 29P is considered the most volcanically active comet in the solar system. It’s one of around 100 comets known as “centaurs” that have been pushed out of the Kuiper Belt — a ring of icy comets lurking beyond Neptune – into a closer orbit around the Sun between those of Jupiter and Neptune, after NASA (opens in new tab).
On November 22, an amateur astronomer named Patrick Wiggins noticed that the brightness of 29P had increased dramatically spaceweather.com (opens in new tab). Subsequent observations by other astronomers showed that this increase in luminosity was the result of a massive volcanic eruption – the second largest observed on 29P in the last 12 years, the researchers said British Astronomical Association (opens in new tab) (BAA). The biggest eruption in that time was a huge eruption in September 2021.
An outbreak of this size is “quite rare”. Cai Stoddard Jones (opens in new tab), a PhD student at Cardiff University in the UK who snapped a follow-up image of the eruption of 29P, Live Scence said. “It is [also] hard to say why this one is so big.”.
The explosion was followed by two smaller eruptions on November 27 and 29, according to the BAA.
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Unlike volcanoes on Earth, which spew boiling hot magma and ash from its mantle, 29P spews extremely cold gases and ice from its core. This unusual type of volcanic activity is known as cryovolcanism, or “cold volcanism.”
Cryovolcanic bodies, which include a handful of other comets and moons in the Solar System, such as Saturn’s Enceladus, Jupiter’s Europa, and Neptune’s Triton, have surface crust surrounding a mostly solid ice core. Richard Miles (opens in new tab), a BAA astronomer who has studied 29P, told Live Science. Over time, solar radiation can cause comets’ icy interiors to sublimate from solid to gas, causing pressure to build up beneath the crust. If solar radiation also weakens the crust, this pressure causes the outer shell to rupture and cryomagma to shoot into space.
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The cryomagma of comets like 29P consists mostly of carbon monoxide and nitrogen gas, along with some icy solids and liquid hydrocarbons, which “may have provided some of the raw materials from which life on Earth arose,” NASA officials wrote.
The cryomagma from 29P’s most recent outburst extended as far as 34,800 miles (56,000 km) from the comet and is traveling at an estimated speed of about 805 mph (1,295 km/h), according to the BAA. The plume “probably contained more than a million tons of ejecta,” Miles added.
Photos of the erupting comet also show that the cloud formed an irregular Pac-Man-like shape, suggesting the eruption originated from a single point or region on the comet’s surface, according to Spaceweather.com.
These observations support previous research suggesting that 29P’s eruptions are related to its rotation. Miles and Stoddard-Jones believe that the comet’s slower rotation causes solar radiation to be absorbed more unevenly on the comet, which triggers the flares. So far, the comet’s outbursts coincide with its 57-day rotation period, the researchers said.
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Researchers also suspect that 29P’s most explosive flares follow a cycle based on its orbit around the Sun. Several large eruptions were noted between 2008 and 2010, and now two massive explosions have occurred in the last two years, Miles said. It is therefore likely that there will be at least one other major eruption of 29P by the end of 2023, he added.
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However, it’s less clear how this prolonged flare cycle works because unlike most other comets, which approach the Sun during a specific period of their orbits, 29P has a largely circular orbit, meaning it never gets much closer to the Sun comes than his average distance, Stoddard-Jones said.
29P has been largely ignored by the astronomical community since its discovery in 1927, but as new evidence of its unusual volcanic activity emerges, it’s starting to be taken more seriously, Miles said. “There is clearly something new to discover in the study of 29P.”
That James Webb Space Telescope Early next year, 29P is set to come under closer scrutiny, he added.
