Lost comet Comet Shoemaker–Levy 9, which collided with Jupiter in 1994. Lost comet A comet is "lost" when it has been missed at its most recent perihelion passage. This generally happens when data is insufficient to reliably calculate the comet's orbit and predict its location. The "D/" designation is used for a periodic comet that no longer exists or is deemed to have disappeared. Lost comets can be compared to lost minor planets, although calculation of comet orbits differs because of nongravitational forces, such as emission of jets of gas from the nucleus. Some astronomers have specialized in this area, such as
Thomas Bopp Planetarium at the university. In 1997, as comet Hale–Bopp reached its brightest point, Bopp's brother and sister-in-law were killed in a car accident after photographing the comet. "This has been the best week of my life. And the worst," Bopp told a "National Geographic" reporter. Bopp and his father Frank have had an asteroid named after them, , discovered October 5, 1991, by Carolyn and Gene Shoemaker. In 1997 Gene Shoemaker and his wife, both famous for co-discovering comet Shoemaker–Levy 9, were involved in a fatal car crash while observing Hale-Bopp. Gene died in the crash and his ashes were