Tuesday, December 08, 2009

Flashback: The 2001 Leonid Meteor Shower

While sorting through some boxes of accumulated stuff from my days as a long-haul trucker, I came across this little memento from eight years back. It was scrawled in my nearly illegible scribble on the back of an envelope (that had contained the bills of lading for the shipping container full of fake Chinese christmas trees I had picked up the previous day at the Port of Los Angeles and was currently hauling to the K-Mart Distribution Center outside of Denver). I don't know who my intended audience was; I suspect they never saw it. So after a significant delay, y'all get first crack at it (transcribed as is, unedited).

For background; the return of the Leonid Meteor storms around the turn of the millenium had been eagerly anticipated for decades. It had been on my must-see list of upcoming astronomical events since I was a child. Astronomers had nailed down 2001 as one of the likely years for this to happen, and November 18th was the night. The outbursts in the previous few years had been poorly situated for North Americans; this one was expected to especially favor us.


Late November 2001, on the road somewhere in the Western U.S.

Among the many hats I wear are those of the professional trucker and amateur astronomer. For the last week I kept a close eye on meteor forecasts and load assignments to try to get myself parked in clear, dark skies on the night of Nov. 18. All came together and I was in the desert in Utah under clear skies with a magnitude 6 visual limit. The only sky glow, mysteriously hanging under Leo, proved to be the Zodiacal Light. When my alarm got me up at midnight, I walked away from the stray lights of the highway and found the sickle of Leo just rising. Almost immediately, a shining yellow Leonid streaked across the sky from east to west, nearly from horizon to horizon. Over the next few minutes three more appeared low in the east, two creeping along the horizon and a third launching vertically like a rocket. This was the confirmation I needed; I returned to my truck, bundled up, and went back to settle in for the show.

By 1:00 I had counted 25 Leonids including those first four; quite an impressive tally, I thought, with the radiant only a few degrees above the horizon. In the next half hour I counted 33 Leonids; between 1:30 and 2:00 a total of 75 of them flashed into view. I put an exclamation mark beside that total in my notes, having never counted that many meteors in a half hour before. But the Leonids were just warming up.

I count meteors the simple, old-fashioned way. I just keep a tally in my head, and every 30 minutes write the number down, to enjoy the show without having to be fumbling with notepads and clocks and lights constantly. But before long I found myself having to use my fingers to keep track of how many hundreds of Leonids I had seen in each half hour. The numbers climbed exponentially: 141, 223, then 546! It might not have been of the magnitude of the colossal Leonid storms of earlier decades, but I knew I was seeing something that I would probably never see again.

At the peak of the display the sky reminded me of a forest filled with lightning bugs, flashing and winking out in ones, twos, and threes. I could just gaze at the radiant, which was quite well up by then, and see meteors flashing every few seconds all around. Along with the classic fast-flying yellow Leonids with trails lingering for a second or two, there were quite a few faint streaks that could have been easily overlooked if there had not been so many of them. The abundance of Leonids made the radiating pattern obvious, and the occasional sporadic meteors seemed almost comically lost, like someone trying to go up the down escalator.

It is hard to say if it was real or just an illusion created by random scattering, but the Leonids certainly did appear to be clustered. Pairs and threesomes seemed to come in rapid succession; at one point five Leonids flashed in one second, giving a brief hint of what the intense storms might look like. Whether there is any real definition of a "meteor storm" I do not know, but I would tend to think of this display as a heavy shpwer, not a full-on storm. The meteors were easily countable, they were not constantly filling the sky, and they did not create the feeling of "racing through space towards the radiant." These all feature prominently in the eye-witness accounts of historical Leonid storms. Whatever it is called, it was a sight to remember!

Leonids kept falling at about 1000 per hour from about 3:00 until 4:00. After that they tapered off only slowly; bright meteors were still visible several times per minute at the end of the night in the dawn twilight. It seemed to me that notable fireballs were notably lacking for the first half of the show; after 3:30 brilliant white fireballs with terminal bursts and trails that persisted for several minutes became common. At about 4:40 when the shower had dwindled to "only" 500 meteors per hour, fatigue and cold won out and I returned to the sleeper of my truck. Even then it was hard to leave the continuing rain of shooting stars outside my windshield, and I kept peeking every half hour or so until dawn finally brought the show to an end.


As a postscript, I in fact did see a second Leonid outburst the following year from my newly-acquired farm in Tennessee, which was almost as impressive as the 2001 show.


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