- VALLEY FORGE, Pa. (AP) -- The glint in the sky looks at first like a big star
but ignites spectacularly, rivaling the moon's brightness. Then, in a few
seconds, it fades.
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- "I just say 'Wow,' when I see a
really good one," said Terry Pundiak, an Allentown physician and amateur
astronomer. "I'm surprised they don't cause more reports of UFO sightings."
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- This newfound heavenly body is no unidentified
flying object but one of a year-old constellation of low-orbiting satellites
called Iridiums, and spotting their five- to 30-second flashes is the latest
celestial fad.
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- Planetariums lead nighttime Iridium vigils.
Internet message boards burn with anecdotes and technical details. Backyard
stargazers spend evenings counting how many they can spot with the naked
eye.
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- "On any given night you have a good
chance of seeing them, and you don't need a telescope," said Ron Dantowitz,
astronomer at the Museum of Science in Boston. "You just need at least
one good eyeball."
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- Motorola first launched the rotating
Iridium satellites in May 1997, and the first flares were reported the
following August.
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- Each Iridium has three mirror-like antennas
about the size of a door. Unlike the surfaces of other satellites, which
are concave or not very reflective, Iridium antennas are flat, silver-coated
Teflon panels. When sunlight hits at a certain angle, an Iridium casts
a brilliant reflection up to 30 times brighter than Venus, reaching a patch
on Earth of about 20 square miles.
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- "I saw one that practically burned
my retinas out," said Randy John, a computer programmer and amateur
astronomer in Pleasant Hill, Calif.
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- With about 70 Iridium satellites in orbit
-- including about a half-dozen broken, or tumbling, satellites that emit
less predictable flashes -- observers just about anywhere in the world
can see a dozen flares of varying brightness in a single evening. The brightest
flares can even be seen through clouds, in daylight or from the inner city.
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- The satellites' orbits are so punctual
that the flares can be predicted to the second.
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- Queens University chemistry professor
Brian Hunter of Ontario was probably the first to report an Iridium flare,
followed shortly by Don Gardner of Columbia, Md. Most of the discoveries
are chronicled on a dozen or so Web sites now dedicated to Iridium flare
pictures, predictions and anecdotes.
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- The flares quickly became eye candy for
professional astronomers as well. In October 1997, a rooftop flare-spotting
session was held at the 48th International Astronomical Congress in Turin,
Italy.
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- "As fascinating as the natural night
sky may be, on any given night it does not vary much, except for the short-lived
streaks of falling stars or meteors," said solar physicist Bart De
Pontieu of Palo Alto, Calif. "To me, artificial satellites add a touch
of motion and surprise to the otherwise steady, unchanging night sky."
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- Astronomers feared at first that satellite
flares would be disruptive because they can be mistaken for a comet or
meteor and leave a sky-long white streak in photographs.
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- "It could be misconstrued as landing
lights from an airplane or even a nova," said amateur astronomer Jeff
Hunt of Charlotte Hall, Md., who maintains one of the foremost flare-predicting
Web sites.
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- But most skywatchers have found the flares
are predictable enough that they aren't a problem. Moreover, the brilliant
flares have been a boon to stargazing.
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- "The Iridium satellites could become
astronomers' unwitting partners in building an interest in the night sky
for the 'Star Wars' generation, which has been hard to impress with telescopic
views of deep sky objects," said amateur astronomer Russell Sipe of
Anaheim Hills, Calif.
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- Sipe said he witnessed the "wow
factor" of Iridiums at a softball game in southern California recently,
when he knew that an Iridium satellite would flare overhead.
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- "We stopped the game for a few minutes.
All of a sudden there are 25 or so people looking up, watching in awe.
And for those few seconds, that had them thinking about space and astronomy,"
Sipe said.
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- Spotting satellites as a hobby started
back in the 1950s with the launch of the first satellite, the Russian Sputnik,
and its U.S. followers. At the time, newspapers published satellite schedules,
fueling a craze in satellite watching.
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- Motorola's $3.4-billion digital satellite
fleet was named after the element iridium with the atomic number 77, the
number of satellites that were expected to be launched. Each one is 13
feet long and 1,500 pounds, with an antenna panel designed to and pick
up and beam phone signals.
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- The fleet, which is not made of iridium,
is the basis of a new global cellular phone system expected to begin this
fall.
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