Leonid Meteors Predictions

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Esko Lyytinen, who made the most accurate prediction for the 1999 Leonid meteor storm [MRB 8, 33-40 (1999)], has now made his predictions for this millennium year’s encounters between the Earth and the various meteor trails emitted by Comet Temple-Tuttle. These always occur near November 17-18 during the present decade. Every year at that time, at least a meteor shower always occurs, producing typically 30-60 meteors per hour. This annual display is called the Leonid meteors. However, at times when the

parent comet has recently passed by, the meteor densities can rise dramatically, perhaps even exceeding the threshold for a meteor storm – 1000 meteors per hour. In 1999, the peak rate was 4000 meteors per hour from Turkey, Cyprus, and the Middle East.

Predictions for November 1999

Results of 1999 Predictions

Although the meteor rate is again expected to be at storm levels in November 2001, with predictions by some experts exceeding 10,000 per hour (Lyytinen thinks 6000 per hour is a better estimate), the favored area of visibility will be the Western Pacific – out of commuting range for most potential observers! So considerable interest centers on this year’s events. This is because it will be only the second opportunity to test the models that make these difficult predictions; and because one of the favored areas of visibility will be the Eastern seaboard of the United States. The Earth will approach three different meteor trails this November.

The first meteor trail approached will be that released by the parent comet in 1933, and will occur about 2:50 a.m. Eastern Standard Time (EST), [5 hours behind Universal Time (UT)] on Friday morning, November 17. (Leonids are always visible only in the early morning hours, and are among the fastest meteors of any of the annual showers.) The further east one goes, the higher the radiant will be in the sky, and the greater the number of meteors expected to be seen. The radiant will be in the zenith at the shower peak at about 45° west longitude, 20° north latitude. But it will be high enough for shower visibility from the Eastern U.S. Observations will be hampered by moonlight. The Moon is approaching last quarter, and will be located near the radiant (in Leo) on the sky. However, from clear-sky locations far from city lights and pollution, this encounter should still produce more meteors than any of the regular annual showers. The predicted peak rate is about 200 meteors per hour (making no allowance for moonlight). This portion of this particular meteor trail is predicted to contain primarily faint meteors.

Predictions for November 2000

The second and third trails encountered are on the following morning, November 18, and will also be hampered by moonlight, although a bit less so than on the previous day. The second encounter is with the trail released by the comet in 1733, and will peak at 3:40 a.m. UT, making it visible from much of Europe and northern Africa. The predicted maximum meteor rate under ideal observing conditions is 700 per hour. However, several factors combine to make this prediction especially uncertain. It is affected by what is called the “A2 effect”, which is not usually so important for other predictions, and is not on strong footing either theoretically or observationally. This shower could reach storm levels, or could no-show. Observers are cautioned to temper their expectations accordingly. Whatever happens, the accuracy of this prediction will be especially valuable for improving future predictions.

The third meteor trail encountered will be the one released in 1866. It will also peak at 2:50 a.m. EST, as for the first encounter above; but on November 18 instead of the 17th. That makes it well suited to Eastern U.S. seaboard observers. The predicted peak meteor rate is also 700 per hour, as for the second trail above, but with considerably less uncertainly. Indeed, Meta Research may cooperate with astronomical societies in the Greater Washington, DC region in arranging suitable observing sites and instruction for the public. (Watch our web site, <http://metaresearch.org>, for details.) If the weather cooperates, more meteors should be seen than for any of the predictable annual showers. For most observers, that will mean seeing more meteors than on any previous occasion in their lives.

Observers in other parts of the world should see a fine Leonid shower at typical levels of a bit less than one per minute if viewing conditions are excellent. But the art of making these predictions is not yet so advanced that surprises are ruled out. Especially, the streams containing the brightest fireballs are not yet well-mapped-out. So by all means, have a look.

The best time to check the skies is about two hours before sunrise in your local area, because that is when the Leonid radiant will be highest in the sky without interfering twilight. By about one hour before sunrise, twilight will start to eliminate the fainter meteors from visibility. Moonlight will interfere everywhere, but simply turn your back on it and watch the part of the sky away from the Moon. Assuming no ground lights to interfere, looking away from the Moon should keep your vision dark-adapted. For optimum results, find a place where you can lie back and look upward without need to crane your neck. And remember to dress warmly. Happy meteor hunting!

Predictions for November 2001