HALLEY’S COMET

Compiled by Chilman Sahni

British astronomer Edmund Halley (1656- 1742) was the first to prove that comets travel in orbits, making it possible to calculate when they will next be seen from Earth. He predicted that the comet he saw in 1682 would return in 1759. It did and was named in his honor. The regular 76-year orbit of Halley’s Comet means that we can find historical accounts of its appearances going back more than 2000 years. They were often believed to foretell important events.

Dates Closest to the Sun:     Observations

• 25 May 240 BC:                       Seen in China

• 10 October 12 BC:                   Believed to mark the death of Roman general Agrippa

• 28 June AD 451:                       Believed to mark the defeat of Attila the Hun

• 20 March 1066:                        William (later William the conqueror) believed the comet was a sign of imminent victory over King Harold at battle of Hastings. The comet and the battle feature in the Bayeux Tapestry, made some years later.

• 9 June 1456:                          The defeat of the Turkish army by Papal forces was thought to be linked to the comet.

• 15 September 1682:             Observed by Edmund Halley, who predicted its return.

• 13 March 1759:                      The comet’s first return, as predicted by Halley, proving his calculations correct.

• 16 November 1835:               The American author Mark Twain was born this year. He always believed that his fate was linked to that of the comet, and soon after it reappeared in 1910, he died.

• 10 April 1910:                          There was panic as many believed that world would come to an end.

• 9 February 1986:                    The Japanese Suisei probe, Soviet Vega 1 and Vega 2 and the European Space Agency’s Giotto space probes passed close to Halley’s comet. Astronomers concluded that the comet is made of dust held together by water and carbon dioxide ice.

• 28 July 2061:                           Next due to appear.
  

    
More than 20 comets return more regularly than Halley. The most frequent visitor is Encke’s comet, named after the German astronomer Johann Franz Encke (1791-1865). In 1818 he calculated the 3.3 year period of its orbit. The closest a comet has ever come to Earth was more than 500 years ago. On 20 February 1491, the so-called comet of 1491

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