Devil Comet's Explosive Pattern: City-Sized Space Rock Erupts Every 15 Days

A city-sized comet, nicknamed the 'devil comet' for horn-like eruptions, displays a predictable pattern, erupting every 15 days.

The last event was on December 14, with the next expected on December 29 or 30. Astronomers attribute the eruptions to the comet's two-week spin period, positioning its cryovolcanic vent toward the sun, causing the release of ice and gas.

Cryovolcanic Eruptions of the Devil Comet 12P/Pons-Brooks

Richard Miles from the British Astronomical Association likens Comet 12P to 'Old Faithful,' describing its super cryogeyser that erupts after local sunrise. Designated as a cryovolcanic comet, 12P/Pons-Brooks displays volcanic activity by releasing a mixture of gases and ice as it approaches the sun, causing increased heat and pressure in the nucleus.

This pressure buildup results in the explosive release of nitrogen and carbon monoxide, flinging icy debris through cracks in the nucleus's shell and forming distinctive shapes, such as devil horns or a horseshoe, visible through telescopes.

Approximately the size of Halley's comet, 12P/Pons-Brooks, last visible in 1954, shares a 71-year orbit around the sun, earning it the moniker 'Halley-type comet.' Predicted to be closest to Earth in April 2024, it is expected to reach magnitude +4, potentially visible to the naked eye in May and June 2024.

The brightest visibility is forecasted for June 2, 2024. Named after its discoverers, Jean-Louis Pons and William Robert Brooks, the devil comet returns to our solar system every 71 years, with at least seven significant outbursts observed since the 19th century.

2023 is notable for being on track to match the number of significant outbursts observed in one year. This increased activity adds to the intrigue surrounding Comet 12P/Pons-Brooks and its unique cryovolcanic behavior.

When the Devil Comet Lost Its Horns

The notorious "Devil Comet" marked its fourth eruption on November 14, as observed by amateur astronomer Eliot Herman. The cryogenic outburst, witnessed by Herman just hours after initiation, led to a substantial 100-fold increase in the comet's brightness.

The proximity of the comet, officially designated 12P, to Earth is set to improve as it approaches its closest point on June 2, 2024, coming within 144 million miles (232 million km) of our planet, approximately 1.5 times the distance between Earth and the sun.

Despite the frequent and violent outbursts, the characteristic horns that earned the comet its sinister nickname seemed to be absent after the latest eruption. Astronomers noted new features, including a rare green hue and a mysterious "shadow."

The usually irregularly shaped nucleus of 12P, which causes the distinctive horns during eruptions, appeared to have a perfectly circular coma this time, as observed by Nick James, director of the British Astronomical Association's comet section.

The disappearance of the horns remains unclear, but it is speculated that the frequent eruptions may have played a role in altering the nucleus's irregularities. BAA astronomer Richard Miles suggested that the outflowing gas might have been obstructed by a notch in the nucleus, and the eruptions may have destroyed or damaged this obstruction.

Observations during the third eruption on Halloween showed fewer distinct horns, hinting that the notch might have been affected earlier, potentially explaining the current absence of the characteristic features.