The black spots on Jupiter caused by the impact of Comet Shoemaker-Levy 9 last week are persisting. And they *can* be seen in amateur telescopes if the sky is clear and steady. No one knows how long they'll last -- estimates range from a few more days to a year. Spot A has started breaking up and others are elongating in Jupiter's winds, making it hard to tell some of them apart. The following times are for when the spots are predicted to cross Jupiter's central meridian (the line running between its north and south poles. Be sure to convert to your time zone.
For July 29-30th C 3:54 p.m. EDT July 29th M 5:07 K 5:20 W 5:29 L 7:15 G 8:19 S 8:31 D 8:32 R 8:54 Q 9:20 H 10:20 E 11:55 A 12:46 a.m. EDT July 30th C 1:49 M 3:03 K 3:16 W 3:24
You can extend these predictions for several days by repeatedly adding Jupiter's rotation period: 9 hours 56 minutes. Some spots are much bigger, darker, and thus more visible than others. These include H, K, L, and the elongated complex G-D-S-R. Omitted here are B, P, and Q2, which have not been seen visually; also, F, T, and V are near E and too faint, and is N near Q.
Smaller debris that was in the comet's southwestern tail will keep plowing into Jupiter for weeks. As of today, it is hitting the *near* side in full view from Earth. Any good-size chunks might cause visible flares. The most pieces, and the largest ones, should come soonest. So keep Jupiter's celestial east limb under watch, and be ready to note the time to the second if you see a definite flare. Full comet-crash coverage will appear in future issues of SKY & TELESCOPE.
By now you're probably aware that images of the comet crash were transmitted among scientists worldwide by the vast computer network known as the Internet. For example, a 60-centimeter telescope at the South Pole, the only site able to view Jupiter in darkness around the clock, relayed its images back to the University of Chicago using a satellite-assisted link to the Internet. But the system's real power was demonstrated by how often everyday computer users tapped into the huge cache of comet data. In the past two weeks Internet sites at the Space Telescope Science Institute, NASA's Goddard Space Flight Center, the Jet Propulsion Laboratory, and the European Southern Observatory in Germany have logged roughly *two million* images that were downloaded for private viewing.