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Saturn’s rings are heating the planet’s atmosphere

By using observations from NASA’s Hubble Space Telescope, the retired Cassini probe, and other space missions, an international team of scientists has found that Saturn’s rings are heating the planet’s upper atmosphere – an unexpected phenomenon never seen before in our solar system, which could potentially provide a tool for predicting whether other planets have Saturn-like ring systems.

The evidence of how this heating effect is produced was provided by the detection of an excess of ultraviolet radiation in the form of hot hydrogen in Saturn’s atmosphere, indicating that something was contaminating and heating the upper atmosphere from the outside. According to the experts, the most plausible explanation for this phenomenon is that icy ring particles raining down onto Saturn’s atmosphere cause the heating effect, influenced by Saturn’s gravitational field pulling the particles into the planet. Cassini probe’s measurements at the end of its mission in 2017 confirmed that many particles are falling in from the rings.

Using archival ultraviolet-light (UV) observations from four space missions that studied Saturn, and calibrating them with measurements from Hubble’s Space Telescope Imaging Spectrograph (STIS), the scientists discovered that the spectra were consistent across all the missions, suggesting that the steady “ice rain” from Saturn’s rings is the best explanation.

These findings suggest that the slow disintegration of Saturn’s rings influences the atomic hydrogen of the planet, changing the composition of the upper atmosphere. The discovery of the heating effect of Saturn’s rings on the planet’s upper atmosphere could provide a tool for predicting whether other planets around other stars have Saturn-like ring systems and thus deepen our understanding of the evolution of planets and their atmospheres in our solar system and beyond.

“This [discovery] 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,” said study lead author Lotfi Ben-Jaffel, an astrophysicist at Sorbonne University in Paris and the University of Arizona. “We are just at the beginning of this ring characterization effect on the upper atmosphere of a planet. We eventually want to have a global approach that would yield a real signature about the atmospheres on distant worlds. One of the goals of this study is to see how we can apply it to planets orbiting other stars. Call it the search for “exo-rings.’”

By Andrei Ionescu, Staff Writer

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