Comet of the Week: ISON C/2012 S1

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Special Topic: Close Asteroidal Encounters

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Comet of the Week: 29P/Schwassmann-Wachmann 1 1927j

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Special Topic: Comets and Meteor Showers

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It is now generally accepted that the planets in our solar system formed via the accumulation of smaller bodies dubbed “planetesimals” – which in turn formed from the accumulation of dust grains and (in the outer and thus colder regions) gas molecules – early in its history. Due to the early sun’s rotation the infalling …

JANUARY 19, 2006: NASA’s New Horizons mission is launched from Cape Canaveral, Florida. After a somewhat distant flyby of the main-belt asteroid (132524) APL in June 2006 and a gravity-assist encounter with Jupiter in February 2007, New Horizons encountered Pluto and its system of moons in July 2015 – providing our first detailed view of …

Perihelion: 2020 January 2.79, q = 1.859 AU  It has been obvious for several decades that the dividing line between “comets” and “asteroids” is, in a word, nebulous, and some facets of this will be explored in future “Special Topics” presentations. One group of objects that are included within this discussion were initially referred to …

Two weeks ago I devoted the “Special Topics” presentation to the subject of near-Earth asteroids. Up until almost the end of the 19th Century all of the over 400 asteroids that had been discovered up to that time orbited within the “main asteroid belt” between Mars and Jupiter, and the astronomers of that era were …

JANUARY 12, 1910: A group of diamond miners in the Transvaal in South Africa spot a brilliant comet low in the predawn sky. This was the first sighting of what became known as the “Daylight Comet of 1910” (old style designations 1910a and 1910 I, new style designation C/1910 A1). It soon became one of …

Perihelion: 2007 January 12.80, q = 0.171 AU After the LIncoln Near-Earth Asteroid Research (LINEAR) program based in New Mexico became operational in early 1998, the discovery rate for both asteroids (including, certainly, near-Earth asteroids) and comets exploded dramatically. This trend has continued on up to the present day with the various subsequent surveys that …