Comet Shoemaker–Levy 9 were observed, with the largest coming on July 18 at 07:33 UTC when fragment G struck Jupiter. This impact created a giant dark spot over across, and was estimated to have released an energy equivalent to 6,000,000 megatons of TNT (600 times the world's nuclear arsenal). Two impacts 12 hours apart on July 19 created impact marks of similar size to that caused by fragment G, and impacts continued until July 22, when fragment W struck the planet. Observers hoped that the impacts would give them a first glimpse of Jupiter beneath the cloud tops, as lower material was exposed
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,