Saturn's rings are heating up the outermost layer of the planet's atmosphere: the phenomenon, never seen before in the Solar System, was discovered by putting together 40 years of ultraviolet observations made by various famous missions, such as Cassini and Voyager 1 and 2, calibrated thanks to data collected by the Hubble Space Telescope.
The discovery, which will help find alien worlds equipped with a ring system, is published in Planetary Science Journal by a research team led by Lotfi Ben-Jaffel, who works at the Paris Institute of Astrophysics and at the University of Arizona .
The telltale sign of this unprecedented phenomenon is an excess of ultraviolet radiation visible as a line of hot hydrogen in the spectrum of Saturn's atmosphere: the peak of radiation means that there is something contaminating and heating the upper part. of the atmosphere from outside.
The most plausible explanation is that the heating is caused by the fall of frozen particles from the rings of Saturn, due to the impact of micrometeorites, the bombardment of particles from the solar wind, solar ultraviolet radiation or electromagnetic forces that collect electrically charged dust .
All this happens under the influence of Saturn's gravitational field, which attracts particles to the planet.
The slow rain of ice from the rings had already been documented 'live' by the Cassini spacecraft at the end of its mission in 2017, but "its influence on the planet's atomic hydrogen comes as a surprise," explains Lotfi Ben-Jaffel.
The excess of ultraviolet radiation had also been detected by several missions, but only thanks to the Hubble Stis spectrograph was it possible to calibrate all the observations and understand that the anomalies recorded were not artifacts.
