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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.