Astronomical naming conventions order of their discovery. Thus Bennett's comet has the systematic designation C/1969 Y1. Halley's Comet, the first comet to be identified as periodic, has the systematic name 1P/1682 Q1. Comet Hale–Bopp's systematic name is C/1995 O1. The famous Comet Shoemaker–Levy 9 was the ninth periodic comet jointly discovered by Carolyn Shoemaker, Eugene Shoemaker, and David Levy (the Shoemaker–Levy team has also discovered four non-periodic comets interspersed with the periodic ones), but its systematic name is D/1993 F2 (it was discovered in 1993 and the prefix "D/" is applied, because it was observed to crash into Jupiter). Some comets were first
David H. Levy biography of Pluto-discoverer Clyde Tombaugh in 2006, and his tribute to Gene Shoemaker in "Shoemaker by Levy". He has provided periodic articles for "Sky and Telescope" magazine, as well as "Parade Magazine", "Sky News" and, most recently, "Astronomy Magazine". Periodic comets that Levy co-discovered include 118P/Shoemaker–Levy, 129P/Shoemaker–Levy, 135P/Shoemaker–Levy, 137P/Shoemaker–Levy, 138P/Shoemaker–Levy, 145P/Shoemaker–Levy, and 181P/Shoemaker–Levy. In addition, Levy is the sole discoverer of two periodic comets: 255P/Levy and P/1991 L3. On February 28, 2010, Levy was awarded a Ph. D. from the Hebrew University of Jerusalem for his successful completion of his thesis "The Sky in Early Modern English Literature: A Study