As the thermonuclear fires of the sun continue to explode like billions of successive hydrogen bombs, huge quantities of atomic particles are blasted out of the sun. These particles- hydrogen ions, free electrons, protons, and neutrinos- fly away from the sun in all directions at great speeds. This solar wind is what rips particles out of the head of a comet, making a tail that sweeps back from the comet in the direction of the solar wind. The solar wind is also the cause of auroras, or northern lights. As the electrically charged particles of the wind near the Earth’s magnetic field, they are deflected and made to move along the lines of magnetic force toward the poles. As the charged particles shower through the air, they glow.

From: How the World Works by: Boyce Rensberger