01 March, 2011

Rocketing Masses with Fuzzy Tails

The word 'comet' comes from a Greek word that means 'hairy one'. A comet sometimes looks like a star with a hairy tail. But a comet is not a star. Like the Moon, a comet has no light of its own. A comet shines by reflecting the light of sun. Like the Earth, a comet revolves around the Sun, so it may appear again and again.
Some scientists claim that comets are composed largely of ice. The rest of their bodies contain of  bits of iron and dust and perhaps few huge pieces of rock. When sunshine melts the ice in a comet, great clouds of gas go streaming behind them which eventually look like their huge fuzzy tails.
Long ago when there were no streetlights and the air was very clean, eveyone could see comets in the sky without using any kind of telescopes.
Unlike the stars that shine every night on the night sky, comets appear quite suddenly. In the past People used to think that they would bring bad luck such as floods, hungry times, or sickness for human beings on earth. Thats why comets were considered as bad omen in past.

The English astronomer Edmond Halley, who lived over 200 years ago, discovered about 24 different comets in his life time. One that keeps coming back was named fo him because he worked out when it would return. Halley first saw it in 1759, and it reappeared in 1835, 1910, and 1986. The next time it comes near the Earth will be in the year 2060.How old will you be then?
American author Mark Twain, who wrote Tom Sawyer, was born in 1835 on a day when Halley's Comet could be seen in the sky. Just as he predicted, he died when Halley's Comet was again seen in the sky, in 1910.

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