aurora

Concise Oxford English Dictionary © 2008 Oxford University Press:
aurora /ɔːˈrɔːrə/

▶noun (pl. auroras or aurorae /-riː/)

• 1 the Northern Lights (aurora borealis) or Southern Lights (aurora australis), a natural phenomenon characterized by the appearance of streamers of coloured light in the sky near the earth's magnetic poles and caused by the interaction of charged particles from the sun with atoms in the upper atmosphere.

• 2 literary the dawn.

– derivatives
auroral adjective.

– origin ME: from L., ‘dawn, goddess of the dawn’.