Comet nucleus comets include 3D/Biela in 1846, Shoemaker–Levy 9 in 1992, and 73P/Schwassmann–Wachmann from 1995 to 2006. Greek historian Ephorus reported that a comet split apart as far back as the winter of 372–373 BC. Comets are suspected of splitting due to thermal stress, internal gas pressure, or impact. Comets 42P/Neujmin and 53P/Van Biesbroeck appear to be fragments of a parent comet. Numerical integrations have shown that both comets had a rather close approach to Jupiter in January 1850, and that, before 1850, the two orbits were nearly identical. Cometary nuclei are among the darkest objects known to exist in the Solar
David H. Levy of Allusions to Celestial Events in Elizabethan and Jacobean Writing, 1572–1620." Starting in 2015, Levy has been donating his observing logs, which he has kept continuously since 1956, his personal journals since 1958, and his comet search records since 1965, to the Linda Hall Library of Science Library in Kansas City. The observing records are also on-line at the website of the Royal Astronomical Society of Canada. He lives in Vail, Arizona and is married to Wendee Levy. Levy and his wife hosted a weekly internet radio talk show on astronomy, which ended on February 3, 2011, with a planned