The solar wind consists of protons, electrons and other heavierirons and they have velocities of several hundred km per second.Moving charged particles experience a force when in an externalmagnetic field. The Earth's magnetic field at the equator has avalue of approximately 3 x 10-5 T and is directed to thenorth. This field strength extends into the space above the earth.Consider a solar wind proton moving at 5 x 105 m/s thatapproaches the earth from outer space along a line toward thecenter of the earth that lies on the plane of the equator. In whatdirection will the proton be deflected? Will it reach the earth'ssurface? What if the particle were an electron? Why is the Earth'sMagnetic field important to life on the Earth?
