JPL Helps Unlock Mystery of Silicon in Jupiter and Saturn

NASA’s Jet Propulsion Laboratory in Pasadena helped uncover why silicon may hide in Jupiter and Saturn using a brown dwarf nicknamed “The Accident.”

Scientists using the James Webb Space Telescope detected silane (SiH?), a silicon-hydrogen molecule never before confirmed in gas giant atmospheres. The molecule appeared in the infrared spectrum of The Accident, a faint brown dwarf 50 light-years from Earth. The discovery, published Sept. 4 in Nature, may explain why scientists can’t find silicon in the upper layers of Jupiter and Saturn.

“This brown dwarf is a ball of gas like a star, but without an internal fusion reactor, it gets cooler and cooler, with an atmosphere like that of gas giant planets,” said Peter Eisenhardt, project scientist for the WISE mission at JPL. “We wanted to see why this brown dwarf is so odd, but we weren’t expecting silane. The universe continues to surprise us.”

Citizen scientist Dan Caselden first spotted The Accident in 2020 through NASA’s Backyard Worlds: Planet 9 project, which used data from the NEOWISE mission, managed by JPL. The object’s infrared spectrum includes features typical of both young and old brown dwarfs, making it difficult to detect using conventional search algorithms. Earlier surveys missed it because of its faintness and unusual spectral signature.

Lead author Jackie Faherty of the American Museum of Natural History said the finding could help scientists understand the chemistry of more familiar planets. “We’re not finding life on brown dwarfs,” Faherty said, “but we’re setting up the scientists who will one day analyze rocky, potentially Earth-like planets.”

Researchers believe The Accident formed in an oxygen-poor environment where silicon could bond with hydrogen to create silane. Jupiter and Saturn likely formed in oxygen-rich regions, where silicon bonded with oxygen and sank below observable layers. The silane detection in The Accident suggests similar molecules may exist deep in gas giants’ atmospheres, hidden by their reactivity and depth.

The Webb data also revealed methane (CH?), water vapor (H?O), carbon monoxide (CO), and carbon dioxide (CO?) in The Accident’s atmosphere. This chemical profile helps scientists model planetary formation and evolution. The findings provide a rare glimpse into substellar chemistry and may inform future exoplanet studies.

JPL, a division of Caltech, operated both the WISE and NEOWISE missions for NASA’s Science Mission Directorate. The Webb Telescope is an international collaboration led by NASA, the European Space Agency, and the Canadian Space Agency.

For more information, visit NASA’s WISE mission page and Webb Telescope science portal.