The most feasible explanation is that icy ring particles raining down onto Saturn’s atmosphere cause this heating, according to a team of astronomers who analyzed several datasets obtained by the NASA/ESA Hubble Space Telescope, NASA’s Cassini spacecraft, NASA’s Voyager 1 and 2 spacecraft, and the NASA / ESA / SERC International Ultraviolet Explorer mission. This could be due to the impact of micrometeorites, solar wind particle bombardment, solar ultraviolet radiation, or electromagnetic forces picking up electrically charged dust.
“Though the slow disintegration of the rings is well known, its influence on the atomic hydrogen of the planet is a surprise,” said Dr. Lotfi Ben-Jaffel, a researcher at the Institute of Astrophysics in Paris and the Lunar & Planetary Laboratory at the University of Arizona.
“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 gasses that are probably heating the atmosphere at a specific altitude.”
The team’s conclusion required pulling together archival ultraviolet-light (UV) observations from four space missions that studied Saturn.
This includes observations from NASA’s Voyager probes that flew by Saturn in the 1980s and measured the UV excess.
At the time, astronomers dismissed the measurements as noise in the detectors.
NASA’s Cassini mission, which arrived at Saturn in 2004, also collected UV data on the atmosphere (over several years).
Additional data came from Hubble and the International Ultraviolet Explorer, which launched in 1978.
But the lingering question was whether all the data could be illusory, or instead reflected a true phenomenon on Saturn.
The key to assembling the jigsaw puzzle came in the…
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