California
A volcanic comet moving around in the inner solar system has suddenly become extremely violent, blasting out four times in 48 hours. Researchers say that the activity has caused it to spew out so much energy that it is now nearly 300 times brighter than normal. This comet is known as a centaur and is only one among 500 that race around the inner solar system their entire lives.
Known as 29P/Schwassmann-Wachmann (29P), the large icy object measures 60 kilometres. Scientists are scratching their heads, trying to figure out the reason behind its sudden awakening. Notably, the latest explosions are the most violent in more than three years.
Comet 29P is not only a centaur, a rare group of comets, but also a cryovolcanic, or a cold volcano comet, numbering only a few hundred in the universe.
Cryovolcanic comets have an icy shell, or nucleus, filled with ice, dust and gas. Moving near the sun, the comet at one stage soaks up so much radiation that its frosty insides get superheated. When the pressure builds within the nucleus, the shell cracks and the comet's icy guts, or cryomagma, are thrown outside into space.
Also Read: Is Planet Nine lurking in the solar system? We might know in 2025
This leads the comet to become even brighter because its coma — a fuzzy, reflective cloud of cryomagma — expands after an explosion and reflects more of the sun's rays.
Comet 29P experienced its first major eruption on Nov. 2, according to observations listed by the British Astronomical Association (BAA). Three more large outbursts followed in less than 48 hours. BAA astronomers, who have been closely tracking 29P, say that the four eruptions expelled a cloud of debris that reflected 289 times more light than the comet's nucleus.
'Devil Comet' with horns
Last year, a similar comet with "horns" hogged the limelight following several explosions. It was comet 12P/Pons-Brooks, also known as "the devil comet". The horns were a result of the several blasts the comet had.
Experts say something similar can be expected from 29P as well since explosions can lead comets to take on odd shapes.
The last time 29P had an outburst was in November 2022, when it spewed more than one million tonnes of debris into space. Before that, the comet underwent five major explosions in quick succession in September 2021. The Nov. 2 blasts were larger and more violent than this one.
Cryovolcanic comets move around the sun in elliptical orbits and can travel to the edges of the outer solar system for decades, centuries or even thousands of years. Once they return to the inner solar system, they undergo violent explosions and are later flung back to the outer solar system.