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Near-Live Leonid Watching System

Forwarded from George Varros (gvarros@mail.hq.nasa.gov)
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.

            http://leonids.hq.nasa.gov/  

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.

Predictions:

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

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