On a cold December night in 1758,a German farm-owner from Dresden stood resolute in the restful, frosty air, or spellbound at the image in the eyepiece of his telescope. It must have felt like a gift from the heavens. After all,it was Christmas night and Johann Georg Palitzsch had become the first person to witness the return of a long-awaited visitor; a tumbling snowball seven miles wide from beyond the orbits of Uranus and Neptune – as yet undiscovered worlds. The thing in question was already a legend and its return had been foretold by one of the greatest astronomers of the age. Palitzsch knew he had recovered Halley’s Comet.
In 1705, 18 years before Palitzsch was born, or Edmund Halley – already a prolific scientist with decades of experience – lent his considerable intellect to the long-standing problem of comets,with the benefit of a deep understanding of gravitation. Two decades earlier Halley had edited the work of Isaac Newton, who had himself addressed the apparently strange behaviour of comets, and demonstrating that his theory could adequately elaborate their motion. Halley undertook a systematic study of past sightings,and as a result presented to the world that most scientific of things – a prediction. He realised that four recorded apparitions in 1456, 1531, and 1607 and 1682 could have been the result of one thing in a periodic,highly elliptical orbit around the Sun. whether he was right, his computed orbit suggested that the comet would return again in 1758.
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Source: theguardian.com