Comet Shoemaker–Levy 9 brought the impact sites into view for terrestrial observers a few minutes after the collisions. Two other space probes made observations at the time of the impact: the "Ulysses" spacecraft, primarily designed for solar observations, was pointed towards Jupiter from its location away, and the distant "Voyager 2" probe, some from Jupiter and on its way out of the Solar System following its encounter with Neptune in 1989, was programmed to look for radio emission in the 1–390 kHz range and make observations with its ultraviolet spectrometer. The first impact occurred at 20:13 UTC on July 16, 1994, when fragment
Comet Shoemaker–Levy 9 carbon disulfide persisted in the atmosphere for at least fourteen months after the collisions, with a considerable amount of ammonia being present in the stratosphere as opposed to its normal location in the troposphere. Counterintuitively, the atmospheric temperature dropped to normal levels much more quickly at the larger impact sites than at the smaller sites: at the larger impact sites, temperatures were elevated over a region wide, but dropped back to normal levels within a week of the impact. At smaller sites, temperatures higher than the surroundings persisted for almost two weeks. Global stratospheric temperatures rose immediately after the impacts,