November 3, 2005: "I thought some wise guy was shining a
spotlight at me," says Josh Bowers of New Germany, Pennsylvania.
"Then I realized what it was: a fireball in the southern sky. I was doing
some backyard astronomy around 9 p.m. on Halloween (Oct. 31, 2005), and this
meteor was so bright it made me lose my night vision."
Bowers wasn't
the only one who saw the fireball. Lots of people were outdoors Trick or
Treating. They saw what Bowers saw ... and more. Before the night was over,
reports of meteors "brighter than a full moon" were streaming in from
coast to coast.
Astronomers
have taken to calling these the "Halloween fireballs." But there's
more to it than Halloween. The display has been going on for days.
On Oct. 30th,
for example, Bill Plaskon of Jonesport,
Maine, was "observing Mars through a 10-inch telescope at 10:04 p.m. EST
when a brilliant fireball lit up the sky and left a short corkscrew-like smoke
trail that lasted about 1 minute."
On Oct 28th,
Lance Taylor of Edmonton, Alberta, woke up early to go fishing with five
friends. At about 6 a.m. they "noticed a nice fireball. Then 20 minutes
later there was another," he says
On Nov. 2nd in
the Netherlands, "The sky lit up very bright," reports Koen Miskotte. "In the
corner of my eye I saw a fireball about as bright [as a crescent moon]."
And so on....
What's
happening? "People are probably seeing the Taurid
meteor shower," says meteor expert David Asher of the Armagh
Observatory in Northern Ireland.
Every year in
late October and early November, he explains, Earth passes through a river of
space dust associated with Comet
Encke. Tiny grains hit our atmosphere at 65,000
mph. At that speed, even a tiny smidgen of dust makes a vivid streak of
light--a meteor--when it disintegrates. Because these meteors shoot out of the
constellation Taurus, they're called Taurids.
Most years the
shower is weak, producing no more than five rather dim meteors every hour. But
occasionally, the Taurids put on quite a show.
Fireballs streak across the sky, ruining night vision and interrupting fishing
trips.
Asher thinks
2005 could be such a year.
According to
Asher, the fireballs come from a swarm of particles bigger than the usual dust
grains. "They're about the size of pebbles or small stones," he says.
(It may seem unbelievable that a pebble can produce a fireball as bright as the
Moon, but remember, these things hit the atmosphere at
very high speed.) The rocky swarm moves within the greater Taurid
dust stream, sometimes hitting Earth, sometimes not.
"In the
early 1990s, when Victor Clube was supervising my PhD
work on Taurids," recalls Asher, "we came
up with this model of a swarm within the Taurid
stream to explain enhanced numbers of bright Taurid
meteors being observed in particular years." They listed "swarm
years" in a 1993 paper in the Quarterly
Journal of the Royal Astronomical Society and predicted an
encounter in 2005.
It seems to be
happening.
When should you
look? You might see a fireball flitting across the sky any time Taurus is above
the horizon. At this time of year, the Bull rises in the east at sunset. The
odds of seeing a bright meteor improve as the constellation climbs higher. By
midnight, Taurus is nearly overhead, so that is a particularly good time.
According to
the International Meteor Organization, the Taurid
shower peaks between Nov. 5th and Nov. 12th. "Earth takes a
week or two to traverse the swarm," notes Asher. "This comparatively
long duration means you don't get spectacular outbursts like a Leonid meteor
storm." It's more of a slow drizzle--"maybe one every few
hours," says Asher.
A drizzle of fireballs, however, is nothing to sneeze
at. So keep an eye on the sky this month for Taurids.
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