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  • Draconid Meteor Outburst.

  • Presented by Science at NASA.

  • Have you ever felt like the sky is falling?

  • On October 8th you might be right.

  • Earth is going to plow through a stream of dust from Comet

  • 21P/Giacobini-Zinner, and the result could be a storm of

  • Draconid meteors.

  • "We're predicting as many as 750 meteors per hour visible

  • mainly over the Middle East, north Africa, and parts of

  • Europe," says Bill Cooke of NASA's Meteoroid Environment Office.

  • Every six and a half years, more or less, Comet

  • Giacobini-Zinner swings through the inner solar system.

  • With each visit, it lays down a narrow filament of dust,

  • over time forming a network of filaments that Earth

  • encounters every year in early October.

  • "Most years, we pass through gaps between filaments, maybe

  • just grazing one or two as we go by," says Cooke.

  • "Occasionally, though, we hit one nearly head on, and the

  • fireworks begin."

  • 2011 could be such a year.

  • Forecasters at NASA and elsewhere agree that Earth is

  • heading for three or more filaments on October 8th.

  • Multiple encounters should produce a series of variable

  • outbursts beginning around 1600 Universal Time with the

  • strongest activity between 1900 and 2100 Universal Time.

  • Estimates of the meteor rate range from dozens to hundreds

  • of meteors per hour.

  • One respected forecaster, Paul Wiegert of the University of

  • Western Ontario, believes the meteor rate could go as high

  • as 1000 per hour, the definition of a meteor storm.

  • It wouldn't be the first time.

  • Close encounters with dusty filaments produced storms of

  • more than 10,000 Draconids per hour in 1933 and 1946, with

  • lesser outbursts in 1985, 1998, and 2005.

  • Meteors from Comet Giacobini-Zinner stream out of the

  • northern constellation Draco, hence their name.

  • Draconids are among the slowest of all meteors, hitting the

  • atmosphere at a relatively leisurely 20 kilometers per second.

  • The slow pace of Draconid meteors minimizes their danger to

  • satellites and spacecraft and makes them visually distinctive.

  • "A Draconid gliding leisurely across the sky is a beautiful

  • sight," says Cooke.

  • Unfortunately, many of this year's Draconids will go unseen.

  • Glare from the almost-full Moon will reduce the number of

  • meteors visible over Europe, Africa and the Middle East by

  • 2- to 10-fold.

  • The situation is even worse in North America where the

  • shower occurs in broad daylight, from noon to 5:00 pm

  • Eastern Daylight Time, completely obliterating the display.

  • That isn't stopping a group of high-school students from

  • Bishop, California.

  • They plan to observe the shower from the stratosphere where

  • the sky is jet black even at noontime.

  • Led by Science@NASA's Tony Phillips, the 12 students have

  • been launching helium balloons to the edge of space since

  • May of 2011.

  • With more than 95% of Earth's atmosphere below the balloon,

  • the sky above looks almost as black as it would from a

  • spacecraft, perfect for astronomy.

  • "The students are going to fly one of our low-light meteor

  • cameras in the payload of their balloon," says Cooke.

  • "I hope they catch some Draconid fireballs for us to analyze.

  • They could be the only ones we get." Stay tuned for results

  • after October 8th.

  • For more news about things flashing in the night sky, visit

  • science.nasa.gov.

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ScienceCasts。龍捲風隕石爆發 (ScienceCasts: Draconid Meteor Outburst)

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    QAM Chen 發佈於 2021 年 01 月 14 日
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