Comet of the Week: Ikeya-Seki 1965f

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Special Topic: Kreutz Sungrazers

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Comet of the Week: Siding Spring C/2013 A1

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Special Topic: 1I/‘Oumuamua

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To our ancestors of just a few centuries ago, comets were, at best, mysterious objects, very possibly of divine or supernatural origin. When one considers that bright comets could appear anywhere in the nighttime sky, seemingly out of nowhere, and after being visible for a few days or weeks would then disappear, it is little …

MARCH 1, 1705: British astronomer Edmond Halley publishes his calculations of the orbits of the comets of 1531, 1607, and 1682, concluding that they are individual returns of the same comet, and that that comet would return in 1758. His prediction turned out to be correct, and the comet has been named in his honor. …

Perihelion: 1976 February 25.22, q = 0.197 AU  What I consider to be the best comet I have ever seen was missed by most of the general public. Part of this was due to the fact that it put on its best appearance in the sleepy hours before dawn, but a large part of it …

Once it had become clear that comets are bona fide members of the solar system just as planets and asteroids are, the question then becomes just what their physical nature might be. While they may appear to be fairly large in our nighttime sky, the fact that background stars shine through their tails and their …

FEBRUARY 23, 1988: David Levy obtains the final visual observation of Comet 1P/Halley during its 1986 return, using the 1.5-meter telescope at Catalina Observatory in Arizona. The comet was located 8.0 AU from the sun and appeared at 17th magnitude.  FEBRUARY 24, 1979: The U.S. Defense Department satellite P78-1 is launched from Vandenberg Air Force …

Perihelion: 1943 February 6.72, q = 1.354 AU  The name of Fred Whipple is legendary in cometary astronomy. He spent several decades as an astronomer and professor at Harvard University, and is best known for developing what he called the “icy conglomerate” model of a comet’s nucleus (more commonly referred to as the “dirty snowball”) …