Leonid Meteors, 2004
In the 2004 Observer's Handbook of the Royal Astronomical Society of Canada, meteor experts Margaret Campbell-Brown and Peter Brown indicate that this year's peak activity should occur on the morning of Nov. 17. They cite 09:00 GMT, which corresponds to 4 a.m. ET and 1 a.m. PT. This time is highly favorable for North Americans, especially those in the eastern United States and eastern Canada.
Other meteor researchers, however, such as Jeremie Vaubaillon of France, David Asher of Ireland and Esko Lyytinen of Finland, have examined Leonid prospects for this year and also suggest watching for some meteor activity two days later, on Nov. 19. A brief bevy of 30 to 60 Leonids per hour may seen, but the time frame when these meteors are predicted to be most numerous (approximately 19:00 to 22:00 GMT) favors observers in Asia and Australia (where it will be the early morning hours of Nov. 20).
The meteors will appear to emanate from out of the so-called "Sickle" of Leo, but prospective viewers should not concentrate on that area of the sky around Leo, but rather keep their eyes moving around to different parts of the sky. The parent body, comet 55P/Tempel-Tuttle, passes its dust trail through the orbit of the Earth around November 18-22 every year, but the magnitude or peak rate of meteor encounters varies on a regular three-decade cycle.
Most Leonid particles are tiny and will vaporize very high in the atmosphere due to their extreme speed (about 44 miles per second, or almost 71 km/sec), so they present no threat to people on the ground or even in airplanes.
It is only when these small rocks (or meteoroids) enter the Earth's atmosphere that they are called meteors. They make a dramatic and beautiful entrance, burning up and producing a short glowing trail in the night sky that rarely lasts more than a second or two. The temperature of the meteor trail can reach about 4,600 degrees Celsius (8,312 Fahrenheit). Most meteors are completely destroyed at altitudes between 80 and 110 kilometers, but those that make it to the ground are given yet another name: meteorites.
Public observers of this year's meteor shower and fireballs are invited to report their results online with various astronomical organizations.
Recent years (from 1998 to 2002) have seen some exceptional Leonid meteor showers and storms in some years. The last one occurred in 2002 but, from the results of computations, it appears that no other storm is expected for the coming decade. At present, no Leonid storm until at least 2033 has yet been identified.
Three years ago, "Leonid meteor storm yielded rich research results for NASA astrobiologists," said Dr. Peter Jenniskens, a NASA astronomer based at Ames Research Center and principal investigator for an airborne research mission to collect data unhampered by ground lights and most local weather conditions. "Findings to date indicate that the chemical precursors to life -- found in comet dust -- may well have survived a plunge into early Earth's atmosphere."