aurora

noun (plural auroras or aurorae /ôˈrôrē/)

• 1a natural electrical phenomenon characterized by the appearance of streamers of reddish or greenish light in the sky, usually near the northern or southern magnetic pole.

  [borealis from Latin, 'northern', based on Greek Boreas, the god of the north wind; australis from Latin, 'southern', from Auster 'the south, the south wind']

  The effect is caused by the interaction of charged particles from the sun with atoms in the upper atmosphere. In northern and southern regions it is respectively called aurora borealis or Northern Lights and aurora australis or Southern Lights

• 2 [in singular] literary the dawn.