Zdenek Sekanina Zdenek Sekanina Zdenek Sekanina (born 12 June 1936, Mladá Boleslav, Czechoslovakia (now Czech Republic)) is a Czech-American astronomer and scientist. In 1959, Sekanina started to study astronomy at Charles University in Prague, where he was graduated in 1963. Since 1980, he has been working at the Jet Propulsion Laboratory. His main areas of professional study are meteors and interplanetary dust as well as the study of comets. In the course of his investigations, he dealt with Halley's comet, the Tunguska event, as well as the break-up and impact of Comet Shoemaker–Levy 9 on Jupiter. He was involved in the data
Eugene Merle Shoemaker Institute in 1965. Coming to Caltech in 1969, he started a systematic search for Earth orbit-crossing asteroids, which resulted in the discovery of several families of such asteroids, including the Apollo asteroids. Shoemaker advanced the idea that sudden geologic changes can arise from asteroid strikes and that asteroid strikes are common over geologic time periods. Previously, astroblemes were thought to be remnants of extinct volcanoes — even on the Moon. In 1993, he co-discovered Comet Shoemaker–Levy 9 using the 18-inch Schmidt camera at Palomar Observatory. This comet was unique in that it provided the first opportunity to observe the planetary