 Calculations showed that its unusual fragmented form was due to a previous closer approach to Jupiter in July 1992 . At that time , the orbit of Shoemaker – Levy 9 passed within Jupiter 's Roche limit , and Jupiter 's tidal forces had acted to pull apart the comet . The comet was later observed as a series of fragments ranging up to 2 km ( 1 @.@ 2 mi ) in diameter . 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 ) or 216 @,@ 000 km / h ( 134 @,@ 000 mph ) . The prominent scars from the impacts were more easily visible than the Great Red Spot and persisted for many months . 
