Leonid Predictions: 1999 and Beyond

The 1998 Leonid shower provided an excellent show, but it eluded all attempts of scientists to predict what it was going to be like. Using data from the 1998 shower, a number of groups have issued predictions for what can be expected during the 1999 Leonid shower. The question is: Will predictions for 1999 be any better than they were for 1998?

One group, Asher, Bailey and Emel'yanenko, have performed an analysis involving the resonances of Jupiter on the particles released from Comet T-T, and they claim that the large meteors seen in 1998 were caused by remnants of the 1333 apparition! These particles were trapped in the 5/14 resonance of Jupiter (Monthly Notices of the Royal Astronomical Society 304, L53, 1999) which the Earth encountered in 1998. Becuase the resonance is now passed, they predict that the meteors seen in 1999 and 2000 will be primarily from the 1866, 1899 and 1932 T-T apparitions, and will have a more normal distribution of sizes.

A second observer, Rainer Arlt with the International Meteor Organization, noted that the activity levels in the 1998 shower followed a similar pattern as in the 1965 shower, and predicts that the activity in 1999 may follow the same shape as in 1966 (though he also warns that the actual numbers are not very predictable).

Joe Rao, in Sky & Telescope, uses the historical record of Earth-comet geometry to predict that 1999 will be the best year for a large number of meteors, and does not rule out the possibility of a meteor storm.

Finally, Rob McNaught and collaborators (Research School of Astronomy and Astrophysics), have analyzed the motions of dust particles emitted from T-T over the past 200 years. Their results indicate a higher rate of meteors in 1999 (peak of 1000-1500 per hour). Interestingly, they also predict that the Leonid meteor shower will continue to improve through the year 2002!

Even with all of the different predictions (not limited to those listed above) there seems to be a general agreement on one thing: all predictions indicate that fewer fireballs will be seen in the next few years than were observed in the 1998 shower.

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