Comet Shoemaker-Levy impact on Jupiter, July 1994. Artist's impression of one of the fragments of Comet Shoemaker- Levy 9 streaking in towards the top of Jupiter's atmosphere. Over 20 fragments, each of more than 1 km diameter, are expected to hit the planet on 18-24 July 1994. The comet was broken apart by Jupiter's gravitational field during a close encounter in July 1992. The energy released in an average impact is expected to be equivalent to about 250,000 hydrogen bombs. These impacts will not be visible directly from Earth, but the effects on the atmosphere will be seen as the impact points rotate into view.