capitalized: the Roman goddess of dawn — compare eos
: a luminous phenomenon that consists of streamers or arches of light appearing in the upper atmosphere of a planet's magnetic polar regions and is caused by the emission of light from atoms excited by electrons accelerated along the planet's magnetic field lines
Luminous phenomenon of the upper atmosphere that occurs primarily at high latitudes. Auroras in the Northern Hemisphere are called aurora borealis, or northern lights; in the Southern Hemisphere they are called aurora australis, or southern lights. Auroras are caused by the interaction of energetic particles (electrons and protons) from outside the atmosphere with atoms of the upper atmosphere. Such interaction occurs in zones surrounding the Earth's magnetic poles. During periods of intense solar activity, auroras occasionally extend to the middle latitudes.