Aurora
An aurora is a natural light display in the sky (from the Latin word aurora, "sunrise" or the Roman goddess of dawn), predominantly seen in the high latitude (Arcti and Antarctic)
regions. Auroras are caused by charged particles, mainly electrons and
protons, entering the atmosphere from above causing ionisation and
excitation of atmospheric constituents, and consequent optical
emissions. Incident protons can also produce emissions as hydrogen atoms
after gaining an electron from the atmosphere.