Comet Shoemaker-Levy 9 (formally designated D/1993 F2, nicknamed String of Pearls for its appearance) was a comet that broke apart and collided with Jupiter in July 1994, providing the first direct observation of an extraterrestrial collision of solar system objects. These fragments collided with Jupiter's southern hemisphere between July 16 and July 22, 1994, at a speed of approximately 60 km/s (37 mi/s). Read more
In July of 1994, the fragments of Comet Shoemaker-Levy 9 collided with Jupiter. Exactly 15 years later, in July of 2009, there was another impact. Amateur astronomer Anthony Wesley captured the first image of the 2009 impact at his home observatory in Australia. Observatories such as the NASA Infrared Telescope Facility, Gemini North, Keck, and the Hubble Space Telescope quickly followed up on the discovery, taking astronomers back to those SL9 impact days in 1994.