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Week 40


Comet of the Week: The Great Comet of 1882

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Special Topic: Carbonaceous Chondrites

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SEPTEMBER 27, 1858: A British portrait painter and photographer, William Usherwood, takes a photograph of Comet Donati 1858 VI, the first photograph ever taken of a comet. No copies of Usherwood’s photograph are known to exist. Comet Donati is next week’s “Comet of the Week.”  SEPTEMBER 27, 1990: The Hubble Space Telescope observes Comet Levy …

Perihelion: 1882 September 17.72, q = 0.008 AU  What can arguably be considered as one of the brightest and most spectacular comets of the entire 2nd Millennium was a Kreutz sungrazer, one of the most pre-eminent representatives of that class of objects that is the subject of a future “Special Topics” presentation. It was first …

In an earlier “Special Topics” presentation I described how meteorites are classified based upon their respective compositions. As I indicated in that presentation, the majority of known meteorites are the “stony” meteorites composed primarily of various silicates, and of these, most contain small, roughly spherical particles called “chondrules” that are primarily made up of silicates …