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August 13, 1999:
Skywatchers around the globe enjoyed a modest Perseid meteor
shower during the predawn hours of August 12 and 13, 1999. Observers
in Europe and North America reported seeing 40 to 60 meteors
per hour around the time of the Perseid maximum.
Right: On August 12, 1995 this Perseid
meteor appeared as bright as a
full moon and left a visible smoke
trail that could be observed in binoculars
for as much as 6-8 minutes.
The 1999 Perseid meteors were numerous, but fireballs were rare.
The meteors which made up this year's shower tended to
be fast, brief, and no brighter than about 2nd magnitude.
Image credit:
the Northeast Florida
Astronomical Society.
Meteor PingsWhile most observers looked for the Perseid meteors with their eyes, some enthusiasts used ham radios to listen to the shower. When fast-moving meteoroids strike Earth's atmosphere they heat and ionize the air in their path. The luminous ionized trails are not only visually striking -- they also reflect radio waves. During a major meteor shower such as the Perseids, radio signals from TV stations, RADAR facilities, and AM/FM transmitters are constantly bouncing off short lived meteor trails. Whenever a meteor passes by with the correct geometry, listeners hear a brief "ping" on the receiver's loudspeaker.Left: Stan Nelson points his radio antenna toward the Navy Space Surveillance transmitter in Texas. In New Mexico on August 12, 1999, Stan Nelson monitored 217 MHz transmissions from the Navy Space Surveillance Radar located in Lake Kickapoo, TX. The Perseids shower was scheduled to peak at about 2 p.m. in Nelson's time zone while the sun was still out. The bright sunlight, which would be an impediment to visual observers, didn't stop Nelson from detecting the Perseids on the radio. He recorded 30 meteor radar reflections during an interval lasting just over a hour. It's not over yetIf you missed the Perseids shower on August 12 and 13, don't worry, the shower continues at a lower level until August 22. You can watch the action by following the simple observing tips explained in a previous Science@NASA headline, "Here Come the Perseids!" |
Web Links | |
Perseids Live! -site of the live webcast of the 1999 Perseids Leonids Live! -site of the live webcast of the 1998 Leonids Related Stories: |
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