HALLEY'S COMET
It is one of the best-known comets and is named after the English astronomer Edmund Halley.He brought people to understand that: comets were part of the solar system ; travelled in definite paths ; and come near the sun at regular intervals.
Halley found that the paths of comets seen in 1531 and 1607 were precisely the same as the paths of a comet seen in 1682.He concluded that all these observations were of the same comet moving in a set path around the sun. Halley predicted that the comet would be seen again in 1778 and indeed it was.Halley's comet appears on an average every 77years.Chinese astronomers first reported its appearance in about 240 BC.
It is seen in its orbit only as it gets closer to the sun.The comet was photographed 480 million kilometers from the sun in August 1909 at the Helwan Observatory in Egypt.On April 24 1910, it came as near as 89 million kilometers to the sun.On May 21, 1910 , the earth is believed to have passed through the comet's tail.On October 16 1982, at the Palomar Observatory in California, US, the comet was photographed when it was about 1,6 billion km from the sun.The comet was at its closest to the sun on February 9 1986.
The earth passes through the orbit of Halley's Comet each May and October.Left behind fragments of dust may enter the earth's atmosphere and burn-meteor showers occur during these months .