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Researchers have detected an absorption line from an unknown molecule in the spectra of Titan (upper left) and Pluto (lower right). (The colorful spectrograph in this image is of the sun and is not part of the new study.). | Credit: Titan: NASA\/JPL\/Space Science Institute; Pluto: NASA\/Johns Hopkins University Applied Physics Laboratory\/Southwest Research Institute; Spectrograph: NOAO\/AURA\/NSF; with annotations by Harry Baker<\/p>\n
A mysterious wavelength of light is missing from the dwarf planet Pluto and Saturn’s supersized moon Titan, new James Webb Space Telescope<\/a> (JWST) observations show. The surprising discovery hints that these worlds harbor an unknown molecule that has not been seen in any other solar system<\/a> world or exoplanet<\/a> so far.<\/p>\n Every element<\/a> or molecule in the universe absorbs unique wavelengths of electromagnetic radiation<\/a>. Therefore, one of the main ways astronomers study distant worlds \u2014 both inside and outside the solar system \u2014 is by closely examining the light that reflects off them and searching for dark “absorption lines” that correspond to the wavelengths of known chemical compounds.<\/p>\n For example, molecular oxygen absorbs light at 230 nanometers, so if the electromagnetic spectrum of a faraway exoplanet has an absorption line at this frequency, researchers can be confident that its atmosphere contains oxygen, according to a 2021 study<\/a>.<\/p>\n JWST has proved to be exceptionally good at capturing electromagnetic spectra and identifying specific chemicals in exoplanet atmospheres<\/a>, around distant stars<\/a> and within primitive galaxies<\/a>. It has even identified a molecule on one alien world that could point to extraterrestrial life<\/a>.<\/p>\n In a new study, uploaded June 11 to the preprint server arXiv<\/a>, researchers analyzed JWST data from Pluto<\/a> and Titan<\/a>, focusing on very small wavelengths that have been relatively unexplored until now. This revealed a specific absorption line at around 5.11 micrometers in both worlds’ spectra. (These findings have not been published in a peer-reviewed journal yet.)<\/p>\n The James Webb Space Telescope is specially designed to be able to detect subtle absorption signals from distant worlds. | Credit: Getty Images<\/p>\n The team pored through similar studies on other planetary spectra but “did not find any band referenced in these publications that corresponds to the location of the observed absorption in Titan and Pluto,” the researchers wrote in the paper.<\/p>\n A molecular mystery<\/p>\n The discovery is even stranger because there are very few similarities between Pluto and Titan that could explain why they share a molecule not found anywhere else.<\/p>\n Titan is the largest of Saturn’s many moons<\/a> and is even larger than Mercury<\/a>. It is also the only solar system world, other than Earth, that is known to have liquid rivers and oceans<\/a> on its surface. Pluto, on the other hand, is a completely frozen world that’s around half the size of Titan and roughly four times farther from the sun<\/a> than Saturn’s satellite is.<\/p>\n Both worlds do have similar atmospheres that are rich in methane and nitrogen. However, the researchers are confident that the molecule responsible for the 5.11-micrometer absorption line is located on both worlds’ surfaces, not in their atmospheres.<\/p>\n Titan and Pluto are very different worlds. Saturn’s largest moon has liquid on its surface and is around four times closer to the sun than the dwarf planet. | Credit: Getty Images<\/p>\n Pluto’s absorption line is around three times thicker than Titan’s, meaning the mystery molecule is likely much more abundant on the dwarf planet. But on Titan, the molecule seems to be unevenly distributed, with a stronger absorption line on its trailing side \u2014 the hemisphere opposite to its forward momentum around Saturn \u2014 than on its leading side.<\/p>\n RELATED STORIES<\/p>\n The researchers proposed that it could be benzene \u2014 a ring-shaped hydrocarbon \u2014 mixed with an unknown molecule, or some form of acetylene or ketene ice. However, much more work is needed to prove that any of these potential candidates are responsible for absorbing this specific wavelength, they wrote.<\/p>\n![\"An](\"https:\/\/www.newsbeep.com\/us\/wp-content\/uploads\/2026\/07\/a0535b89829f3c3574e21d6dd5452c3b.jpeg\"\/)
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