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Halley's comet

This is undoubtedly the best known comet. In 1705, the English astronomer Edmond Halley calculated the return of a comet for 1759. He had noted the periodic return of the comet every 76 years. Sure enough, in 1758, sixteen years after his death and only a few months in advance, the comet returned.

The nucleus of the comet is composed of a mixture of ice and dust particles. It is irregular in shape and measures 16 km long by 8 km wide. Hills, valleys and even craters can be made out on its surface; gas escapes from the craters, feeding the comet's tail.

Its first known appearance was in 240 BCE, and its latest was in the winter of 1986.

Giotto and Halley's comet

Giotto and Halley's comet


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