Oort cloud that their occurrence in the outer-planet region would be several times higher than in the inner-planet region. This discrepancy may be due to the gravitational attraction of Jupiter, which acts as a kind of barrier, trapping incoming comets and causing them to collide with it, just as it did with Comet Shoemaker–Levy 9 in 1994. Most of the comets seen close to the Sun seem to have reached their current positions through gravitational perturbation of the Oort cloud by the tidal force exerted by the Milky Way. Just as the Moon's tidal force deforms Earth's oceans, causing the tides to
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