The 1966 Leonid meteor storm photographed at Kitt Peak Observatory.
Every year in mid-November the earth passes through a debris stream left behind by comet 55P/Tempel-Tuttle. This comet returns to the inner solar system every 33 years, leaving as it goes small bits of dust, most no larger than a sand grain. Each passage leaves a stream in a slightly different place. Once the comet returns to the outer solar system, the debris left behind starts to spread out along the path. The earth passes through different streams that have different densities of particles, which causes substantial variability in the number of meteors seen.
The densest debris trail closely follows the comet, so every 33 years or so the Leonids are considerably more active. At those times meteors burn up in the atmosphere at the rate of thousands per hour, and such events are called meteor storms (the term is applied to any rate over 1000 per hour).
The greatest meteor storm recorded was the Leonids of 1966. At the Kitt Peak Observatory in Arizona, observers estimated the peak rate, just before 5:00 a.m. to be 40 meteors per second – 144,000 per hour! I remember my Mom getting us up to see it, and although I didn’t count meteors, my memory is that it seemed like a fireworks display. The next likely opportunity for a similar storm is when the comet next visits the inner solar system in 2031.
Leonid meteors do not hit the ground. The comet material isn’t metallic or rocky enough to survive entry. And the Leonids move faster than most meteors, so they burn up higher in the atmosphere than average. The reason the Leonids move so fast is that the comet and its debris trails orbit the sun in the opposite direction of Earth. The result is a relative velocity of over 160,000 miles per hour.
As for this year, on November 17 we pass through the debris trail left behind in 1466. It tends to be a bit thicker than others, so we might be treated to a heavy shower of up to 500 meteors per hour. The best viewing is typically before dawn local time because that is when your location is headed most directly into the stream. Unfortunately, this year favors observers in Asia, because we will pass through the densest part of the stream at about 3:40 p.m. Kansas City time.
Still, it’s worth looking up Monday night or Tuesday morning. Meteor showers are not always predictable.
More info about this year’s shower: Space.com, NASA
Historical info about the Leonids: NASA
Info about the 1966 storm: Space.com, NASA
Comments
Mr. Spencer,
I think 500 per hour is much more than realistic. The max for this shower will probably be 120 per hour. There may be short bursts where the EZHR will be 500. This means that it would be the equivalent of 500 meteors per hour if in fact it did last for an hour, but these bursts may last 1 to 15 minutes or something like that.
Meteor Mark
meteorblog.com
Shouldn't you say a little sometime about whether we can see any of the shower at all due to light pollution?
The comments by phacops and Meteor Mark are both well-taken. A dark sky location is always required to see the maximum number of meteors in any shower, and here in the metro we are not in such a location. The maximum I used came from the NASA source I linked, and it is the peak rate estimated in that report. At any rate, since the peak occurs mid-afternoon in KC, a lower rate is indeed more realistic for us.
Thanks for the info!
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