New findings on Comet 12P/Pons-Brooks, also known as the "Devil Comet," provide the strongest evidence yet that comets may have delivered water to Earth. Researchers, led by Martin Cordiner of NASA's Goddard Space Flight Center, used the Atacama Large Millimeter/submillimeter Array (ALMA) and NASA's Infrared Telescope Facility to analyze the water in the comet's coma.
Key Discovery
The team measured the ratio of deuterium ("heavy" hydrogen) to normal hydrogen (D/H) in the comet's water. This ratio acts as a chemical fingerprint to trace the water's origin. The D/H ratio found in Comet 12P/Pons-Brooks is "virtually indistinguishable" from the water on Earth's oceans.
Significance
This discovery is particularly significant because it addresses a long-standing question about the origin of Earth's water. While previous studies of other comets, including some Halley-type comets, have shown a different D/H ratio, this new finding suggests that at least some comets could have been a source of our planet's water. This strengthens the theory that comets, along with asteroids, played a crucial role in making Earth habitable by delivering essential elements for life.
The "Devil Comet"
The comet earned its nickname in 2023 after a cryovolcanic outburst caused its coma to distort into a horned, asymmetrical shape. 12P/Pons-Brooks is a cryovolcanic comet, which means it erupts with gas and ice. It's a Halley-type comet with a highly elliptical orbit, taking about 71 years to orbit the Sun.
Catch a recap of the 'devil comet's' journey in this video. Comet With Horns? The Return of the 'Devil Comet' 12P/Pons-Brooks!