Johns Hopkins University Applied Physics Laboratory
Lessons from our Innermost Planet:Mercury's Magnetosphere and Magnetic Field
The intensity of Mercury's surface magnetic field is only 1% that of Earth's so the planetary body occupies a huge fraction of the magnetosphere at Mercury. Moreover, there is no conducting ionosphere at Mercury so the interaction between the solar wind and planetary magnetic field is markedly different than at Earth. The MESSENGER Discovery mission has provided a wealth of data from its over 30 months of orbital observations revealing intense magnetic reconnection, plasma precipitation to the surface, an enigmatically simple planetary offset dipolar field, and the presence of field-aligned Birkeland currents. The stark differences from Earth's magnetosphere provide important tests of our understanding of magnetosphere dynamics and solar wind interactions.