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Some of the data was mistaken as noise when first collected up to 40 years ago, and researchers failed to recognize its significance until now. “When everything was calibrated, we saw clearly that the spectra are consistent across all the missions,” announced Lotfi Ben-Jaffel, lead author of the new research published in Planetary Science Journal on Thursday, and a researcher at the Institute of Astrophysics in Paris and the Lunar & Planetary Laboratory, University of Arizona, in a statement.
“This was possible because we have the same reference point, from Hubble, on the rate of transfer of energy from the atmosphere as measured over decades. It was really a surprise for me. I just plotted the different light distribution data together, and then I realized, wow – it’s the same.”
The researchers traced the increased levels of Lyman-alpha UV radiation to Saturn’s atmosphere, and concluded some external process must be exciting the hydrogen atoms. The most plausible explanation is that the icy particles in Saturn’s rings are crashing down onto Saturn’s atmosphere, causing it to heat up.
These bits and pieces get dislodged by colliding with micrometeorites, or by solar wind particle bombardment, solar ultraviolet radiation, or electromagnetic forces picking up electrically charged dust. Once they are knocked out of place, Saturn’s gravity pulls them in.
“Though the slow disintegration of the rings is well known, its influence on the atomic hydrogen of the planet is a surprise,” Ben-Jaffel said. “From the Cassini probe, we already knew about the rings’ influence. However, we knew nothing about the atomic hydrogen content.”
“Everything is driven by ring particles cascading into the atmosphere at specific latitudes. They modify the upper atmosphere, changing the composition. And then you also have collisional processes with atmospheric gases that are probably heating the atmosphere at a specific altitude,” he explained.
The team believe this phenomenon could provide astronomers with a new way to look for ring systems on exoplanets. If a spacecraft detects similar excess UV radiation bands in the upper atmosphere of a faraway planet, it could mean it might be supporting a ring system like Saturn’s.
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Source: Astronomers discover never-before-seen phenomenon on Saturn • The Register