Every element has a unique set of absorption and emission lines that create spectral signatures. These signals are key information for astronomers studying faraway objects—but what happens when there’s no good match for a particular signature? While studying Pluto and Saturn’s largest moon Titan, researchers spotted a missing band of light in their spectral signatures, specifically at the 5.11-micrometer line. However, after searching past datasets and literature, they weren’t able to find any suitable matches for whatever molecule was responsible for this phenomenon. In other words, Pluto’s and Titan’s surfaces may harbor an unknown molecule—a substance that we’ve never seen anywhere else in our solar system and beyond. A paper detailing the results has been accepted for publication in Astronomy & Astrophysics and is currently available as a preprint in arXiv.
“We have a few candidates, but it will not be a simple compound,” Bruno Bézard, the study’s first author and a researcher at the Paris Observatory, told New Scientist. “Whatever it is, it will be a surprise.” Close but far Pluto and Titan don’t look much alike externally, but both possess nitrogen-rich atmospheres with some methane. Photochemical effects create a “ubiquitous organic haze” that eventually trickles down to shape the surface morphology of Pluto and Titan, according to the paper. Researchers behind the latest paper selected a narrow spectral window least affected by the haze to investigate the surface beyond the foggy atmosphere.
