Comet Shoemaker-Levy 9

Astronomers on Earth discover a comet like none seen before: having flown close to Jupiter in July 1992, the comet has broken into multiple pieces in a configuration that its discoverers call “a string of pearls.” Calculations of the orbit of the newly detected comet, named Shoemaker-Levy 9 after the team that discovered it, reveal something stunning: the orbit of the fragments will bring them back to Jupiter in just over a year, at which point they are expected to collide with the planet rather than pass it by or go into orbit. Not only does this give Earth-based astronomers time to coordinate observations, but NASA has an ace in the hole: the entire event will be witnessed by the unmanned Galileo probe as it makes its final approach to the giant planet.