Unusual “Horned” Volcanic Comet Erupts in Rare Event After 70 Years
A fascinating celestial event has caught the attention of astronomers worldwide. The comet 12P/Pons-Brook (12P) has erupted, causing it to “grow horns” and shoot supercold “magma” into space. This eruption marks the first time in nearly seven decades that this comet has been seen erupting.
Known as a cryovolcanic comet or cold volcano, 12P is composed of a solid nucleus filled with a mixture of ice, dust, and gas. It is surrounded by a cloudy gas called a coma. However, unlike most comets, the gas and ice within 12P’s nucleus can build up to a point where the comet violently explodes, releasing its frosty contents, known as cryomagma, through cracks in its shell.
On July 20, astronomers observed a major outburst from the comet. It suddenly became 100 times brighter than usual, capturing the attention of multiple experts. This increase in brightness occurred when the comet’s coma expanded, releasing gas and ice crystals from its interior, reflecting more sunlight back to Earth.
By July 26, the coma of the comet had expanded to a staggering 143,000 miles (230,000 kilometers) in diameter, over 7,000 times wider than its nucleus. The expanded coma presents an irregular shape, resembling horns or the iconic Millennium Falcon spaceship from Star Wars.
Richard Miles from the British Astronomical Association explained that the comet’s irregular coma shape is likely due to an irregularity in the nucleus itself. The outflowing gas was obstructed by a protrusion on the nucleus, creating a “notch” in the expanded coma. As the gas moves away from the comet, the shadow becomes more noticeable. However, the expanded coma will eventually disperse, and the irregular shape will disappear.
This eruption from 12P is the first major event observed in nearly 70 years. The comet’s orbit takes it too far away from Earth, making it challenging to detect its outbursts.
With an orbital period of around 71 years, 12P travels to the farthest reaches of the solar system before reaching its closest point to the sun on April 21, 2024. It will make its closest approach to Earth on June 2, 2024, potentially granting Earthlings a front-row seat to more eruptions in the coming years.
However, 12P is not the only volcanic comet of interest. In recent years, astronomers have also observed significant eruptions from another comet, 29P/Schwassmann-Wachmann. This comet is known to be the most volatile volcanic comet in the solar system.
In December 2022, astronomers witnessed the largest eruption from 29P in 12 years, releasing approximately 1 million tons of cryomagma into space. Furthermore, in April of this year, scientists accurately predicted one of 29P’s eruptions for the first time. The increase in brightness indicated that more gas was leaking out of the comet’s nucleus before it erupted.
As astronomers continue to study these volcanic comets, they hope to unravel the mysteries surrounding their eruptions and gain further insights into the dynamic nature of these icy celestial objects.