Will the annual Leonid meteor shower deliver a last hurrah this year and next or fade toward insignificance sooner rather than later? By analyzing new data provided by the observed performance of the shower in the last several years, experts are favoring the former.
Here are the facts: The Leonid shower rises to a crescendo on or near November 17 every year, delivering a modest display of about 10-15 visible "shooting stars" per hour for a string of about 30 years. Then, on a cycle of roughly 33 years, the Leonids roar to life with meteors appearing at the rate of hundreds to thousands per hour in a single year or in several consecutive years.
The meteor streaks appearing all over the sky during the shower are generated by swarms of small dust and ice particles shed from a comet called Tempel-Tuttle. The chance of the Earth bumping into a particularly dense strand of Comet Tempel-Tuttle debris improves whenever that comet passes near Earth -- once every 33 years. The particles of debris collide with Earth's upper atmosphere in parallel streams. Each particle disintegrates in a blaze of light as it plows through the air at more than 100,000 miles per hour, appearing and disappearing from view in a fraction of a second. By perspective, the parallel paths of these fiery pinpoints create the illusion that the meteors are originating from a single "vanishing point" in the sky, called the shower's radiant. All Leonids radiate from Leo, a constellation that at this time of year lies above the horizon from about 11 p.m. onward.
According to a detailed article appearing in the November 2001 issue of Sky and Telescope magazine, the favored night for West Coast observers this year will be November 17-18 (Saturday night-Sunday morning), with a distinct peak in activity occurring near 2 a.m. After that, rates will likely decline somewhat. Observers several time zones to the west of us have a shot at observing a second, probably larger peak in activity during the predawn hours at that longitude. For us, the second peak will occur during daylight on Sunday morning and therefore will be unobservable.
The same calculations that are predicting this year's Leonid activity also prognosticate high rates for the Leonids in 2002. However, next year the bright light of the full moon will largely spoil the view. This year's shower will be unaffected by moonlight.
Some meteors during this year's shower can be observed from San Diego's brightly lit urban area, but any serious meteor-watching must take place well away from the city at dark mountain or desert locales. No telescope is required; simply lie back in a warm sleeping bag at any site with an unobstructed view of the whole sky. If there's not much activity going on (due to obscuring clouds or a failure of the predictions) and you'd rather get some sleep, try setting an alarm every hour or so to monitor the shower's progress.