An aurora is a bright, colorful display of light in the night sky. Aurorae are produced when charged particles from the Sun (usually solar wind particles, but sometimes coronal mass ejections as well) enter Earth’s atmosphere. The particles are guided to the north and south magnetic poles by Earth’s magnetic field. Along the way, these particles ionize some of the gas molecules they encounter by drawing away electrons from those molecules. When the ionized gas and their electrons recombine, they glow in distinctive colors; and the glowing gas undulates across the sky.