Comet of the Week: 21P/Giacobini-Zinner 1984e

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Special Topic: Deflection Strategies

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Special Topic: “Small Bodies” Moons

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Special Topic: The Kuiper Belt

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MAY 24, 1981: American astronomer Harold Reitsema and his colleagues, observing from Arizona, detect a possible moon of Neptune during an apparent occultation of a background star. This object was confirmed by Voyager 2 during its flyby of Neptune in August 1989 and is now known as Larissa and designated as Neptune VII.  MAY 24, …

Perihelion: 44 B.C. May 25.0, q = 0.22 AU  The appearance of a bright comet is certainly a stimulus of important scientific investigations, and, under the right circumstances, in today’s society can also be a focus for popular culture, at least for a while. In more ancient times, however, when comets were still widely considered …

The general topic of meteorites was discussed as a “Special Topics” presentation four weeks ago. The large majority of meteorites that are known are not especially large, being of the order of a few kg in mass; with only a handful of exceptions, even the larger ones tend to have a mass of no more …

MAY 17, 1882: Observers in the path of a total solar eclipse that crossed central Egypt see and photograph a bright comet during totality. Comet Tewfik X/1882 K1, which was never seen again, was an apparent Kreutz sungrazer, and is this week’s “Comet of the Week.” Solar eclipse comets, in general, are the subject of …

Perihelion: 1882 May 17.5, q < 0.01 AU  On May 17, 1882, the path of a total solar eclipse crossed northern Africa, the Middle East, and southern Asia. As total eclipses go, it was a relatively short one, with the maximum duration of totality – which occurred in present-day Turkmenistan – being only 1 minute …

One of the most spectacular and awe-inspiring celestial sights is that of a bright, long-tailed comet – a “Great Comet,” the subject of a previous “Special Topics” presentation. On average, these appear about once a decade, and I have been privileged to have witnessed four of them during the half-century I have been observing comets …