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Ice and Stone


In any orbital configuration involving two, and only two, objects – for example, Earth and the sun – the orbital motion can be solved directly from Isaac Newton’s Law of Universal Gravitation; the mathematical solution is complete and analytical. As soon as additional objects are added to the mix, however, things become much more complex, …

OCTOBER 4, 2020: The main-belt asteroid (1679) Nevanlinna will occult the 7th-magnitude star HD 224945 in Pisces. The predicted path of the occultation crosses Newfoundland, part of the Maritime Provinces of Canada, the northeastern through the south-central U.S. (including Houston, Texas), north-central Mexico (including the northern regions of Monterrey, Nuevo Leon), and the southern Pacific …

Perihelion: 1858 September 30.46, q = 0.578 AU  Among the many individuals who made important contributions to astronomy during the mid-19th Century was the Italian astronomer Giovanni Donati, who observed from the Observatory of Florence and who was Director of that institution from 1864 until his death (at age 46) in 1873. He made the …

The “Special Topics” presentation three weeks ago discussed actions that we might take should we detect an asteroid that appears will impact Earth. The first and foremost task is the collection of as much data as possible in order to refine the orbit and the likelihood of an actual impact, and if this continues to …

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 …