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330 BC- Aristotle declairs that comets are just warm exhalations in the upper atomosphere. He related them to the lowest "sublunar" spheres in his system of spherical shells ("History of Comets").
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550 BC- Pythagoreans say that comets are just wondering planets, falling to the horizon ("History of Comets").
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1000 BC- The earliest records of comet observations occurred in China ("History of Comets").
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1267 AD- Thomas Aquanis and Roger Bacon write Opus Tertium where they explain that comets are evil omens ("History of Comets").
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Paolo Toscanelli discovers P/Halley iand many other comets between 1433 and 1472 ("History of Comets").
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The Bright Comet first appeared in 1577 Tycho Brahe observed that the diameter of this comet was four times the diameter of the Moon ("History of Comets").
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The question of how comets travel came up in 1610. Sir William Lower suggested that they move in ellongated elipses. At the same tome Robert Hooke and Giovanni Borelli said that orbits caused them to travel ("History of Comets").
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Edmond Halley computed orbits of many observed comets and demonstrated the reoccurring nature of the Bright Comet ("History of Comets").
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The Bright Comet was from now on called Halley's Comet ("History of Comets").
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Jupiter has an orbit of moving comets; the consecration became known as the Jupiter Family ("History of Comets").
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Halley's Comet was recaptured on telescope in 1758 by Johann Palitzsch ("History of Comets").
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i) “The first spectroscopic observations of comets were made by Giovanni Donati (1864) and by Sir William Huggins (1868) who visually compared the spectrum of comet Winnecke (1868 II) with flame spectra and found that the bands seen in the comet and in the flame, now known as the `carbon' or `Swan bands', were similar” ("History of Comets").
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Scientists find that comets have molecules appear to be in solid or liquid states and conclude that a comet's nucleus is made of ice ("History of Comets").
