Comet Shoemaker–Levy 9 compute the density and size of Shoemaker–Levy 9. Its average density was calculated to be about ; the breakup of a much less dense comet would not have resembled the observed string of objects. The size of the parent comet was calculated to be about in diameter. These predictions were among the few that were actually confirmed by subsequent observation. One of the surprises of the impacts was the small amount of water revealed compared to prior predictions. Before the impact, models of Jupiter's atmosphere had indicated that the break-up of the largest fragments would occur at atmospheric pressures of
Comet Shoemaker–Levy 9 largest impacts. The waves were thought to be travelling within a stable layer acting as a waveguide, and some scientists thought the stable layer must lie within the hypothesised tropospheric water cloud. However, other evidence seemed to indicate that the cometary fragments had not reached the water layer, and the waves were instead propagating within the stratosphere. Radio observations revealed a sharp increase in continuum emission at a wavelength of after the largest impacts, which peaked at 120% of the normal emission from the planet. This was thought to be due to synchrotron radiation, caused by the injection of relativistic