Original: 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 .
Simplified: Comet Shoemaker-Levy 9 ( SL9 , D\/1993 F2 ) was a comet that broke apart and smashed into Jupiter in July of 1994 .