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!