The radiation belts of Earth and Saturn differ more strongly than previously assumed. In these belts, very energetic particles, such as electrons and protons, move around the planet at high velocities – captured by its magnetic field. In the case of the Earth, the solar wind, a current of charged particles from the Sun varying in strength, controls the intensity of the radiation belt both directly and indirectly. The radiation belts of Saturn, however, develop completely independently of the solar wind and are instead decisively influenced by the gas giant’s moons. These results are published today in the journal Nature Astronomy by a group of researchers from the Max Planck Institute for Solar System Research (MPS) in Germany co-leading the most comprehensive study on the subject to date. Key to the new findings are measurements of the MIMI-LEMMS instrument aboard NASA’s Cassini space probe, which explored the Saturn system for more than 13 years before its dive into the planet on the 15th of September this year.