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Forwarded from George Varros (
Subject: Near-Live Leonid Watching System

In anticipation of "higher than normal" meteor activity during this November's annual Leonid Meteor Shower, NASA has created an image library and invites amateur astronomers, photographers and individuals with Single Lens Reflex (SLR) cameras or other imaging equipment, to upload their Leonid meteor photographs or images to the Near-Live Leonid Meteor Watching System.

A Brief Background on the Leonid Meteors:

Every 33 years, there is a higher probability that the Leonid Meteor Shower will turn into a meteor storm. This is caused by the parent comet 55P/Temple-Tuttle and its 33 year orbit around the sun, which nearly intersects that of Earth's. Fortunately, this occurs with Earth and the comet on different sides of Earth's orbit.

As it approaches the inner solar system and is heated by the sun, the comet replenishes its path with tiny bits of material eroded away by the solar wind and radiation. As Earth travels in its path around the sun and encounters this debris stream, the small grains of material in this stream slam into Earth's upper atmosphere at a very high rate of speed becoming incandescent and leaving an ionized and luminous trail that we see as meteor or "falling star".

On an average year, 15 to 20 Leonid meteors per hour can be seen, depending on your local viewing conditions. During a storm year, anything can happen as history has shown. The last major Leonid Meteor Storm occurred on November 16, 1966, peaking for observers in the mid-western United States. Hourly meteor rates were estimated to be as high as 144,000! Historical accounts dating back to the 1833 and 1866 Leonids are fascinating to read! The 1899 and 1932 Leonids were largely missed and it is suspected that Jupiter may have altered the meteor stream's orbit for those years. Studies also suggest 2000, 2001 or even 2002 could be much better than normal years, with significantly higher meteor counts than normal years! The 1999 Leonid Meteor Shower is an event that has been long anticipated by the astronomy community.


The peak of the meteor shower or "storm component" has been predicted by the experts to interact with Earth some time between 01:48 and 04:15 Universal Time, November 18, 1999. Observable hourly rates should be significantly higher than normal years, perhaps on the order of several hundred to several thousand per hour during the peak. However, it must be emphasized that the various components of a meteor shower, such as peak time and hourly rates are extremely hard to predict. The peak time can be off by several hours and recorded counts will certainly vary with local sky conditions, the moon and light pollution, visual obstructions and location on Earth.

If the peak occurs during the earlier predicted time, Asia and Europe will be positioned favorably with the radiant high overhead. If it occurs a few hours past the later predicted time, the western portions of Europe and Africa, along with the East Coast of the United States, will be positioned favorably. This is certainly an event not to be missed and it would be well advised to look for the Leonids during the early morning hours of November 17th and November 19th, due to the uncertainty.

A Scenario For US East Coast Observers:

The radiant or apparent area of origin of the meteors, in the constellation Leo, rises in the east shortly before midnight local time November 17th (November 18, 1999 05:00 Universal Time). No Leonid meteors should be expected to be seen prior to this due to the direction that the meteors travel. The moon will interfere with meteor visibility shortly after the radiant rises. It will be waxing gibbous or just past half full and will be setting around 1:00AM local time. It should be noted that the radiant does rise just after the predicted peak for US East Coast observers. However, if the peak, which is very hard to predict is a few hours late, the US will be able to observe the peak with the radiant higher in the sky!

George Varros

Last Updated: November 26, 2003
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