Maybe the hoopla has died down some, but the black spots on Jupiter caused by the impact of Comet Shoemaker-Levy 9 are enduring. You should be able to spot them through your telescope if the sky is clear and steady. And remember: smaller debris from 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. So keep Jupiter's celestial east limb under watch.
Meanwhile, scientists continue to puzzle over why the spots are dark, and why spectrographs failed to detect water in the impact plumes. Maybe the fragments consisted of something much less icy than a traditional comet, or maybe chemical reactions took place in the rising fireballs that converted the water to other compounds. Recent reports suggest that bursts of radio emission from Jupiter became significantly stronger during encounter week, an indication that the comet's dust was interacting with the Jovian magnetosphere. Full comet-crash coverage will appear in future issues of SKY & TELESCOPE.
Thanks in part to the comet crash, NASA announced on August 3rd that a committee has been established to develop a plan to identify and catalog, to the extent practicable within 10 years, all comets and asteroids that might collide with Earth and cause significant damage. That translates to objects larger than about 1 km in diameter. Eugene Shoemaker will chair the eight-member Near-Earth Object Search Committee. He, of course, is now well known as co-discoverer of Comet Shoemaker-Levy 9.
The Perseid meteor shower is due to peak late Thursday night for North America, and this is one not to miss! There's every reason to believe it could match last year's excellent show -- two British astronomers even predict that this week's display will surpass last year's. And *this* time North America should be ideally positioned. In 1993 Europe and the Atlantic Ocean had the best seats. You'll need to follow two guidelines for good results. First, observe under a sky as free as possible from light pollution. Second, do it very late at night -- at least after midnight, and preferably between 2 a.m. and dawn Friday morning August 12th. With luck, you might see several meteors every minute.
With the Moon nearly new, Comet Nakamura-Nishimura-Machholz might be an appealing target this week. It is approaching 8th magnitude as it sweeps past the bright stars of Cassiopeia. Here are equinox 2000 positions for 0 hours Universal Time:
R.A. (2000) Decl.
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Aug 7 1h 31m +65.7dg
Aug 9 1 15 64.6
Aug 11 0 59 63.2
Comet Shoemaker-Levy Home Page