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A strange volcanic comet has violently erupted, spewing more than a million tons of gas, ice and the “potential building blocks of life” into the solar system.
The volatile comet, known as 29P/Schwassmann-Wachmann (29P), is about 60 kilometers wide and takes about 14.9 years to orbit the Sun. 29P is considered the most volcanically active comet in the solar system. It’s one of about 100 comets, called “centaurs”, that have been pushed out of the Kuiper Belt – a ring of icy comets that lurk beyond Neptune — in a closer orbit around the sun between those of Jupiter and Neptune, according to Nasa (opens in a new tab).
On November 22, an amateur astronomer named Patrick Wiggins noticed that the brightness of 29P had increased dramatically, according to Spaceweather.com (opens in a new tab). Later observations by other astronomers revealed that this peak in brightness was the result of a massive volcanic eruption – the second largest observed on 29P in the past 12 years, according to the British Astronomical Association (opens in a new tab) (BAAA). The largest eruption during this period was a huge explosion in September 2021.
A rash of this size is “pretty rare”, Cai Stoddard Jones (opens in a new tab), a doctoral student at Cardiff University in the UK who took a follow-up image of 29P’s eruption, told Live Scence. “His [also] hard to say why this one is so big.”.
The explosion was followed by two smaller explosions on November 27 and 29, according to BAA.
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Unlike volcanoes on Earth, which eject hot magma and ash from the 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 solar system comets and moons such as Saturn’s Enceladus, Jupiter’s Europa and Neptune’s Triton, have a surface crust surrounding a mostly solid ice core, Richard Miles (opens in a new tab), a BAA astronomer who has studied 29P, told Live Science. Over time, solar radiation can shift the icy interiors of comets from solid to gas, causing pressure to build up beneath the crust. When solar radiation also weakens the crust, this pressure causes the outer shell to crack and cryomagma erupts into space.
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The cryomagma of comets like 29P is mostly carbon monoxide and nitrogen gas, along with some icy solids and liquid hydrocarbons, which “may have provided some of the raw materials that gave rise to life on Earth.” , wrote NASA representatives.
Ejecta from 29P’s most recent flare has stretched up to 34,800 miles (56,000 km) from the comet and is moving at speeds of up to 805 mph (1,295 km/h), according to BAA . The plume “probably had over a million tons of ejecta,” Miles added.
Photographs of the erupting comet also show the plume 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 that suggests that 29P flares are related to its rotation. Miles and Stoddard-Jones believe that the comet’s slower rotation results in a more uneven absorption of solar radiation onto the comet, triggering the flares. The comet’s flares so far tend to match its 57-day rotation period, the researchers said.
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The researchers also suspect that 29P’s most explosive flares follow a cycle based on its orbit around the sun. A number of large eruptions were detected between 2008 and 2010, and now two massive explosions have occurred in the past two years, Miles said. It is therefore likely that there will be at least one other major 29P eruption by the end of 2023, he added.
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However, it is less clear how this longer flare cycle occurs, because unlike most other comets, which approach the sun during a specific period of their orbits, 29P has a largely circular orbit, meaning that ‘it never gets very close to the sun. 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 emerges of its unusual volcanic activity, it is starting to be taken more seriously, Miles said. “There is clearly something new to discover in the study of 29P.”
The James Webb Space Telescope should take a closer look at 29P early next year, he added.
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