November 06, 2013
A detailed analysis of data from NASA’s Cassini spacecraft has directly linked the density of the ionosphere – a region in the upper atmosphere that is dominated by electrically charged particles – at Saturn’s moon Titan to the 11-year boom-and-bust cycle of activity at our sun. The confirmation was possible because of Cassini’s long-term stay in the Saturn system, which began in 2004, and a Swiss-Army-knife-like suite of many instruments.
At planets and solar system bodies with an atmosphere – such as our own Earth – X-rays and extreme ultraviolet radiation from the sun split atmospheric molecules in the upper atmosphere into electrons and ions. Scientists have known about the existence of an ionosphere at Titan since NASA’s Voyager 1 spacecraft flew by the moon in November 1980 and have been studying it close up since Cassini arrived.