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Huge Fireball Dazzles Midwest


Huge Fireball Dazzles Midwest
Marshall Space Flight Center
http://science.nasa.gov/newhome/headlines/ast17nov99_1.htm

November 17, 1999: Tuesday night, on an Illinois highway east of Chicago,
traffic slowed to a crawl as motorists peered at an extraordinary fireball
blazing overhead.

A brilliant fireball attracted stares across the eastern U.S. Tuesday night.
It could be a taste of things to come when the Leonids meteor shower peaks
late Wednesday night and Thursday morning.

"It was of the most beautiful meteors I have ever seen," said Jamie Dresser,
who was driving home from work just after 6 pm CST. "It was so bright that
it lit up the sky for quite a distance. There was a blue corona ... and it
was actually trailing fire for quite a distance. I sincerely look forward to
driving home the next few nights!"

Above: The above 533 KB QuickTime simulation illustrates the relationship
during the Leonids meteor shower between the earth, comet Tempel-Tuttle's
dust field, and the constellation of Leo. The size of the earth and sun have
been exaggerated for clarity. When the earth passes through Tempel-Tuttle's
dust field every November 17-18, the dust particles stream into our
atmosphere and burn up as meteors. The red arrow during the simulation
indicates that a ground-based observer would perceive the meteors as coming
from a point (called the "radiant") within Leo, hence the name Leonids.

Hundreds of reports like this one are pouring in from all over the mid
western United States. Thousands of commuters and star gazers saw what
astronomers call an "Earth grazer" -- a meteoroid or piece of space debris
that travels nearly parallel to Earth's surface as it disintegrates in our
atmosphere. Earth grazers are slow moving and feature vibrant colors in
their long beautiful tails. This one was spotted between 5:50 and 6:05 CST
as it sped over Wisconsin, Michigan, Illinois, Ohio, Kentucky, New York and
several other states.

Tuesday night's fireball was so bright that it was first noticed by many
observers while they were inside brightly lit buildings.

"I was sitting in a Wendy's facing outside and saw the bright orange light
in the sky," recounts Wendi S. Abbott of Cincinnati, OH. "I have no idea how
long it lasted, but I had time to jump up, race over to the window and ask
the family sitting there if they were seeing what I was seeing. The father
said it was just a reflection in the window, but quickly changed his mind.
It finally broke apart in about 3 or 4 pieces before it died out. What an
incredible sight! If this is any indication of what's to come, this will
definitely be a 'once in a lifetime [experience]'."

The trajectory of the fireball was similar in appearance to an aircraft,
flying low and level across the horizon from west to east. Many observers
reported seeing the meteor fragment into many iridescent pieces that
traveled in a line like a string of Christmas lights.

Could this be a taste of things to come in the next 24 hours? Possibly. The
Leonid meteor shower is expected to peak this Thursday morning when the
Earth slices through the debris stream of comet Tempel-Tuttle around 0200 UT
on November 18. Last year a shower of Leonid fireballs (meteors brighter
than magnitude -3) dazzled observers in Europe and the Americas. In 1999
many experts anticipate an even better show. No matter where you live, the
best time to watch will be between midnight and dawn on Thursday. On
Wednesday evening, November 17, before the constellation Leo rises, star
gazers could be treated to more Earth grazers as Leonid meteoroids arc over
the horizon.

With the Leonids just around the corner, it may seem surprising that
Tuesday's fireball was probably not a Leonid. Leonid meteors emanate from a
point in the sky within the constellation Leo, which rises above the eastern
horizon around midnight. At the time of the fireball sighting Leo was about
35 degrees below the northern horizon, which means that Leonid
Earth-skimmers appearing over the horizon would travel roughly north to
south. Most observers reported that the November 16 fireball moved west to
east. While it is possible that this meteoroid was a part of the debris
stream of comet Tempel-Tuttle (the parent of the Leonids), it is far more
likely to be an unrelated, sporadic meteor or perhaps a piece of "space
junk" decaying from low-Earth orbit.

Whatever this fireball was, observers around the world have been seeing
genuine Leonids for over 24 hours. The Leonids Environment Operations Center
at the NASA/Marshall Space Flight Center is managing data from a global
network of observers coordinated by the US Air Force and the University of
Western Ontario. Since early Tuesday morning trained spotters have filed
reports of 8 to 86 meteors per hour (ZHR). In most years, 86 meteors per
hour would be considered a substantial shower, but this could be the year
for a full-fledged Leonids storm. Only time will tell if predictions of more
than 1000 meteors per hour will come true. One thing is sure, the place to
be before dawn on Thursday morning, November 18, is outdoors and looking up!

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