Comet Shoemaker–Levy 9 the surprise of astronomers. As well as these molecules, emission from heavy atoms such as iron, magnesium and silicon was detected, with abundances consistent with what would be found in a cometary nucleus. Although a substantial amount of water was detected spectroscopically, it was not as much as predicted beforehand, meaning that either the water layer thought to exist below the clouds was thinner than predicted, or that the cometary fragments did not penetrate deeply enough. As predicted beforehand, the collisions generated enormous waves that swept across Jupiter at speeds of and were observed for over two hours after the
Great Comet of 1744 "dust striae" seen in the tails of some comets, such as Comet West and C/2006 P1 (McNaught). Chéseaux, on March 9, was the last known observer in the northern hemisphere to see the comet, but it remained visible for observers in the southern hemisphere, some of whom reported a tail length of approximately 90 degrees on March 18. The comet was not seen after April 22, 1744. The comet also was noted in Japanese astronomical records in the "Nihon Odai Ichiran" of the Kanpō era. Researchers have found in Chinese astronomical records that some Chinese observations describe audible sounds associated