Why dayside reconnection is rare at Saturn

The interaction between the flow of solar wind plasma from the Sun and a magnetized planet produces a cavity in the flow known as a magnetosphere. Magnetic reconnection is a fundamental process that disrupts this shielding of the planet by allowing solar wind into the magnetosphere and releasing magnetic energy. Evidence for dayside reconnection at Saturn is very limited compared to Earth and other planets, representing one of the major open issues in Saturnian magnetospheric science. By combining theory, observations, and simulations we show that this is due to the pressure conditions in the vicinity of Saturn's magnetopause, which largely suppress reconnection. Our results demonstrate that solar wind-magnetosphere coupling via reconnection can vary between planets, and we cannot assume that the nature of this coupling is always Earth-like.