Earth’s magnetosphere and outer radiation belt under sub-Alfvénic solar wind

• DOI: 10.1038/ncomms13001
• Publication Date: 2016-10-03T09:38:29Z
• Authors: Noé Lugaz; Charles J. Farrugia; Chia-Lin Huang; Reka M. Winslow; Harlan E. Spence; Nathan A. Schwadron
• Keywords: Magnetosphere of Jupiter; Outer planets; Polar wind; Magnetosheath; Magnetosphere of Saturn

Abstract The interaction between Earth’s magnetic field and the solar wind results in formation of a collisionless bow shock 60,000–100,000 km upstream our planet, as long fast magnetosonic Mach (hereafter Mach) number exceeds unity. Here, we present one those extremely rare instances, when reached steady values <1 for several hours on 17 January 2013. Simultaneous measurements by more than ten spacecraft near-Earth environment reveal evanescence shock, sunward motion magnetopause rapid intense loss electrons outer radiation belt. This study allows us to directly observe state inner magnetosphere, including belts during type wind-magnetosphere coupling which is unusual planets system but may be common close-in extrasolar planets.