aurora
ah-ROR-ah
Curtains, arcs, and ribbons of colored light that appear in the night sky at high latitudes, caused by charged particles from the sun striking the earth's upper atmosphere and exciting gas molecules into luminescence. The aurora borealis (northern lights) and aurora australis (southern lights) are the same phenomenon, mirrored at opposite poles. The colors depend on altitude and gas: green from oxygen at 60 to 150 miles, red from oxygen above 150 miles, blue and purple from nitrogen. An aurora is the planet's atmosphere responding visibly to the sun's breath — the magnetic field channeling the solar wind into the sky and making it glow.
Etymology
Latin Aurora, the goddess of dawn. The lights were named for the dawn because they share its colors and its quality of appearing at the edge of the sky. Borealis from Greek Boreas, the north wind.
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