Shoemaker-Levy 9 has plunged into Jupiter, and the Hubble Space Telescope has moved away to look at other objects in space. Amateur astronomers, however, are still watching Jupiter to see what bruises were left on the mighty planet by the comet crash of 1994. There was tremendous excitement in astronomical circles during the collision of comet and planet. It is now time to see what has been learned from this impact. One question which may never be answered: Was Shoemaker-Levy 9 really a comet, or was it an asteroid instead ? Comets tend to be a mixture of ice, rock and dust, along with other substances, like carbon monoxide, that evaporate quickly to form a halo and a tail. Scientists studying the chemical composition of the spots on Jupiter where Shoemaker Levy 9 (S-L 9) hit thought they might see evidence of water and oxygen, two of the expected products when an icy comet vaporises. But except for one unconfirmed report, researchers have found only ammonia, hydrogen sulphide