Earth's magnetosphere deflecting the supersonic solar wind plasma
Earth's dipole magnetic field creates a magnetopause at the standoff distance R_s ≈ 10 R_E where magnetic pressure B²/2μ₀ balances solar wind dynamic pressure ρv². Upstream, the bow shock (R_bow ≈ 1.3 R_s) decelerates and heats the supersonic solar wind (Mach 6–10) to subsonic in the magnetosheath. A southward IMF B_z opens magnetic reconnection at the dayside, eroding the magnetosphere.