LARGELY PROTECTED. “Earth’s magnetic field (geomagnetic field) changes over time and extends from the Earth’s inner core to where it meets the solar wind. The solar wind is responsible for the overall shape of Earth’s magnetosphere, the sphere protecting the Earth, and fluctuations in its speed, density, direction, and entrained magnetic field strongly affect Earth’s local space environment and technological, biological and ecological systems on the Earth.”
http://file.scirp.org/Html/6-8202044_31922.htm