Comet Shoemaker–Levy 9 electrons—electrons with velocities near the speed of light—into the Jovian magnetosphere by the impacts. About an hour after fragment K entered Jupiter, observers recorded auroral emission near the impact region, as well as at the antipode of the impact site with respect to Jupiter's strong magnetic field. The cause of these emissions was difficult to establish due to a lack of knowledge of Jupiter's internal magnetic field and of the geometry of the impact sites. One possible explanation was that upwardly accelerating shock waves from the impact accelerated charged particles enough to cause auroral emission, a phenomenon more typically associated
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