3. There are times when the night sky glows with bands of color. The
bands may begin as cloud shapes and then spread into a great arc across
the entire sky. They may fall in folds like a curtain drawn across the
heavens. The lights usually grow brighter, then suddenly dim. During this
time the sky glows with pale yellow, pink green, violet, blue, and red. These
lights are called the Aurora Borealis. Some people call them the Northern
Lights. Scientists have been watching them for hundreds of years. They
are not quite sure what causes them. In ancient times people were afraid
of the Lights. They imagined that they saw fiery dragons in the sky. Some
even concluded that the heavens were on fire.