Special Topic: Putting It All Together

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Comet of the Week: Lovejoy C/2011 W3

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Special Topic: Formation of the Planets

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Comet of the Week: The Great Comet of 1680

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APRIL 20, 1910: Comet 1P/Halley passes through perihelion at a heliocentric distance of 0.587 AU. Halley’s 1910 return, which is described in a previous “Special Topics” presentation, was quite favorable, with a close approach to Earth (0.15 AU) and the exhibiting of the longest cometary tail ever recorded.  APRIL 20, 2025: NASA’s Lucy mission is …

Perihelion: 1957 April 8.03, q= 0.316 AU  There weren’t any bright comets that appeared the year I was born, 1958, but two bright comets appeared the previous year. These two objects were the brightest comets to become easily visible from the northern hemisphere since the return of Comet 1P/Halley in 1910.  The first of the …

Throughout “Ice and Stone 2020” I refer to numerous specific objects, including in all of my “Comet of the Week” presentations as well as in several of my “Special Topics” presentations and in the lists of weekly historical events. It is appropriate, then, to discuss how these various objects are designated and named.  The conventions …

APRIL 13, 2029: The near-Earth asteroid (99942) Apophis will pass just 0.00026 AU from Earth, slightly less than 5 Earth radii above the surface and within the orbital distance of geosynchronous satellites. At this time this is the closest predicted future approach of a near-Earth asteroid. The process of determining future close approaches like this …

Perihelion: 2002 March 18.98, q = 0.507 AU  One of the many successful Japanese comet hunters of the 1960s was Kaoru Ikeya who, coming from a family of modest means, built a homemade telescope for the equivalent of US$20 and began to hunt comets with it. He discovered his first comet in 1963 and would …

During the third week of July 1994 the various fragments of Comet Shoemaker-Levy 9 1993e impacted Jupiter, liberating enormous amounts of energy in the process and creating large planet-sized “scars” in Jupiter’s atmosphere that lingered for some time afterwards. (Comet Shoemaker-Levy 9 and these events are discussed in a future “Comet of the Week” presentation.) …