type-A aurora reaches high into
the sky over Fairbanks,
Alaska. This sheet of color
extends vertically through the
atmosphere, and its rays trace
out the Earth's magnetic field
lines. The red light is created
by glowing oxygen more than 120
miles above the Earth's surface,
while the green originates much
lower―only about 60 miles up.
This green light, however, is so
intense that it sometimes even
tints the snow green!