A “star” with a tail
Night after night, a long, shining streak hung in the sky. It looked
like a big, bright star with a glowing tail. Each night it seemed to
grow bigger and brighter. People were terrified. “It’s the end of the
world,” they wailed.For thousands of years, whenever a comet appeared in the sky, people
were afraid of it. Now we know that comets are just part of the sun’s
family. There are many billions of them, going around and around the
sun, just as the planets do. Sometimes a comet’s path brings it close
to the earth, so that it appears as a long, gloving streak in the
night sky.Most comets are balls of frozen gas, like snow, mixed with dust. The
comet does not have a tail until it gets near the sun. Then, the sun’s
heat melts some of the frozen gas, and gas and dust stream off into
space, forming the tail. The tail glows because sunlight shines on the
gas and dust and also releases energy from the gas.The center of a comet’s icy head may be about ten miles (16
kilometers) wide. It is surrounded by a cloud of gas as much as a
million miles (1,600,000 kilometers) wide. A comet’s tail may be as
much as a hundred million miles (160,000,000 kilometers) long.
Comet Bennett
