An Eastward Current Encircling Mercury

Mercury has a terrestrial-like magnetosphere which is usually taken as scaled-down-version of Earth's with similar current system. We examine Mercury's magnetospheric system based on survey magnetic field measured by the Surface, Space Environment, Geochemistry, and Ranging spacecraft well computer simulations. show that there no significant Earth-like ring flowing westward around Mercury, instead, we find, for first time, an eastward (EC) encircling planet near night-side equator altitude ?500–1,000 km. The EC closed dayside magnetopause could be driven gradient plasma pressure diamagnetic current. Thus, not scaled-down Earth magnetosphere, but unique natural space laboratory. Our findings offer fresh insights to analyze data from BepiColombo mission, expected orbit in 2025.