A “Star” with a Tail
For thousands of years, whenever a bright star with a glowing tail appeared in the sky, people were afraid. If it seemed to grow bigger and brighter, some people thought the end of the world was near! Now we know that these “stars” are actually just comets.
Billions of comets travel around and around the sun. Most are balls of frozen gas, like snowballs mixed with dust. They come from two groups of comets near the edge of the solar system. Just beyond Neptune is the group in the Kuiper belt. Beyond that lies the ball-shaped Oort cloud.
At first, comets have no tails. But when a comet gets near the sun, the sun’s heat melts some of the frozen gas. Gas and dust stream off into space, forming a tail. The tail glows because sunlight shines on the gas and dust and also releases energy from the gas.
Picture Credit : Google
