As a model of the physics of the aurora, consider a proton emitted by the Sun that encounters the magnetic field of the Earth while traveling at 4.3 × 105 m/s. B(vector)

(b) Calculate the time required for the proton to complete one circular orbit in the magnetic field.
(c) How far parallel to the magnetic field does the proton travel during the time to complete a circular orbit? This is called the pitch of its helical motion.