The cryovolcanic comet referred to as 29P/Schwassmann-Wachmann went through a significant explosion on February 10 and then transformed into a massive swirl, echoing the form of a snail’s casing or an ancient ammonite.(Image credit: Eliot Herman)
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Recent visuals reveal that, subsequent to one of its most intense bursts in recent memory, a mysterious volcanic comet has morphed into an immense, “fossil-resembling” illumination coil. The astonishing demonstration serves as a reminder of the genuinely perplexing nature of this particular celestial relic.
The singular comet, recognized as 29P/Schwassmann-Wachmann (29P), is a weighty frozen mass approximately 37 miles across — nearly three times the span of Manhattan. It is one of about 500 rare bodies categorized as “centaurs,” which continuously orbit the inner solar system. This comet is also among a more selective tier of cryovolcanic comets, known for sporadically emitting gas and ice across our cosmic vicinity.
The summit of a cryovolcanic comet erupts when its icy exterior, or nucleus, absorbs excessive solar energy. This surplus energy intensely heats the mixture of solid gas and particulate matter — termed cryomagma — within the comet, causing it to transform directly into a gaseous state. The ensuing gas generates internal pressure, ultimately fracturing the nucleus, thereby enabling the spray of icy innards into space. When this transpires, the hazy shroud of material enveloping the comet, referred to as its coma, widens noticeably, amplifying its reflection of sunlight and notably enhancing its visibility in the night’s darkness.
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Spaceweather.com reports that on February 10, Comet 29P underwent a sudden increase in brightness, estimated at roughly a hundredfold escalation in its light output, thus denoting a significant eruptive event.
Experts informed Spaceweather.com that this explosion is among the comet’s “top five” most significant eruptions in the past twenty-four years, with it being the most potent occurrence since a quadruple eruption in October 2024 that resulted in Comet 29P becoming 300 times brighter than usual.
Subsequent to the Feb. 10 outburst, Comet 29P’s coma has grown into a distinguishable spiral configuration.
In the days following the violent eruption, however, scientists began to observe a peculiar feature of 29P’s broadening coma: the reflective atmosphere was unevenly spread around the comet, which is atypical. The cloud instead seemed to have stretched into a unique spiral form.
Eliot Herman, an amateur stargazer and astrophotographer, captured the asymmetrical coma from Chile’s Rio Hurtado valley (as shown above) and noted its resemblance to the remains of an extinct shelled cephalopod known as an ammonoid. Anthony Kroes, a fellow photographer, also captured a striking image of the spiral from Wisconsin, and commented on its “snail-shell appearance.”
Spaceweather.com suggests the odd formation likely stems from an internal spin within the comet relative to its nucleus, causing an uneven ejection of cryomagma from a newly created vent on its icy facade.
This aligns with the instance of “devil comet” 12P/Pons-Brooks, which seemingly sprouted demonic appendages during its initial solar pass eruptions in late 2023. This was attributed to a cut on its exterior, partially obstructing the cryomagma outflow, according to experts.
The interstellar comet 3I/ATLAS, also noted for its traverse through the inner solar system last year, exhibited signals of cryovolcanism, probably discharging cryomagma through multiple emissions.
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Unexplained outbursts
Most cryovolcanic comets, like 12P/Pons-Brooks and the recently sighted Comet SWAN, are comets with elongated orbits residing in the outer reaches of the solar system, migrating towards the sun every few centuries or millennia. Their eruptions occur when nearing our star, triggered by heightened radiation, after which they cease activity and retreat quietly to the outskirts of our cosmic sector.
However, Comet 29P traces a nearly circular path around the sun, maintaining a relatively constant distance. Located between Jupiter and Saturn — roughly six times Earth’s distance from the sun — it receives limited sunlight.
Comet 29P’s orbit around the sun is nearly circular and lies beyond Jupiter, making its cryovolcanism somewhat unexpected.
Nonetheless, Comet 29P averages about 20 eruptions each year. While most are minor, the occasional larger outburst — similar to the recent one — discharges up to 1 million tons of cryomagma into space.
This phenomenon has been perplexing for scientists, as the exact cause of these major outbursts remains unclear, particularly given the apparently consistent conditions of the comet.
Researchers anticipated one of these significant eruptions in April 2023, owing to a minor dimming preceding the comet’s outburst. Nevertheless, the underlying cause remained elusive.
How to see 29P/Schwassmann-Wachmann
Comet 29P has surpassed its peak luminosity. However, it has maintained a heightened brightness because of a second, lesser eruption on Sunday (Feb. 15), which introduced a fresh supply of cryomagma into its coma, as per Spaceweather.com. (The potential for the rejuvenated coma to also evolve into a spiral configuration remains undetermined.)
The comet should still be observable via a decent telescope or stargazing binoculars. As indicated by TheSkyLive.com, it is currently positioned within the constellation Leo.
Richard Miles, an astronomer from the British Astronomical Association who has studied Comet 29P, informed Spaceweather.com that substantial eruptions such as this are frequently succeeded by various smaller eruptions, or “aftershocks,” suggesting the possibility of more outbursts in the days and weeks ahead.
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For those planning to observe under the stars, it may also be worthwhile to watch for Comet C/2024 E1 (Wierzchoś), which is shining vibrantly following its closest approach to Earth on Tuesday (Feb. 17). Scientists suggest that this ice formation could soon be ejected from the solar system indefinitely, similar to 3I/ATLAS, rendering this potentially your only chance to view it.
Two additional interesting comets are expected in April: C/2026 A1 (MAPS), a newly discovered “sungrazer” comet anticipated to shine brilliantly enough for daytime visibility with the naked eye, and the long-period comet C/2025 R3 (PanSTARRS), which may also become visible at night without telescope assistance.
Harry BakerSocial Links NavigationSenior Staff Writer
Harry functions as a senior staff writer for Live Science, located in the U.K. He undertook studies in marine biology at the University of Exeter prior to training to become a journalist. His coverage spans a broad spectrum, encompassing space exploration, planetary sciences, space climatology, climatic variations, zoological behavior, and paleontology. His recent work on the solar maximum earned him the title of “best space submission” at the 2024 Aerospace Media Awards and secured a nomination in the “top scoop” section at the NCTJ Awards for Excellence in 2023. He is also the author of Live Science’s Earth from space weekly series.
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