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The BBC's Chris Riley
"The sky was on fire"
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The BBC's Sue Nelson
On a cloudy night in Kent
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Thursday, 18 November, 1999, 14:20 GMT
In the Leonids' lair
A meteor streaks across the starry sky over the Dead Sea
A meteor streaks across the starry sky over the Dead Sea
By BBC Science's Dr Chris Riley on board Nasa's Leonid mission jet from Tel Aviv, Israel, to the Azores.

Just after two o'clock this morning the sky caught fire at 39,000 feet over Greece.

Meteor chaser Chris Crawford could not believe his eyes. He estimates that his team, strapped into their virtual reality headset displays counted 15,251 meteors.

"That's more than I have seen in 34 years of observing them," he grinned. "Looking through the goggles I could see five or six simultaneously. We've got mountains of data...just mountains!"

We had taken off from Ben Gurian airport a couple of hours before and, as the astronomers started to set up their cameras, streaks of bright white trails were already ripping through the night sky.

Chris Riley will fly on three consecutive nights
Chris Riley will fly on three consecutive nights
Voices called out across the aircraft head sets, directing colleagues to the latest bright fireball which had left a lingering trail of ionised gas suspended in the stratosphere.

At one point both the aircraft had locked onto one of these cosmic "glow worms", recorded its chemistry, computed its height and posted it on their web site before the trail had dispersed.

"The power of technology," laughed Joe Kristel, who had heaved his cumbersome spectrometer onto the trail with brute force to hold the glow worm in his field of view.

And then they came - in their thousands as the Earth crashed through the comets trail. Simply too many to count, they came darting out of Leo, low down to the east and tearing across the starry background.

An impression of the radiant pattern of the Leonids
An impression of the radiant pattern of the Leonids
There were bright ones, faint ones and a giant fireball which hit the atmosphere so hard it broke up into three fragments which scattered below it. I did not know which way to look and nor did the astronomers on board.

Brilliant bursts of light on the horizon from electrical storms over mid-Europe provided a stunning backdrop to the display above and the team started to hunt for sprites. These atmospheric enigmas are bolts of lightning which jump vertically upwards into space from storm cloud tops.

It has long been thought that they might be triggered by meteor trails breaking overhead and short-circuiting the upper atmosphere. From 39,000 feet up, with over twenty cameras pointing out over the storm clouds to the North, there was never a better opportunity to put this theory to the test.

The team did not need to wait long. Two meteor streaks were captured on film apparently triggering sprites in the distance.

For project scientist and life-long meteor chaser Dr Peter Jenniskens, the night was beyond his wildest dreams. "We did get the storm we were looking for and some sprites too," he said.

Space weather

For once the Leonids lived up to expectations and their secrets have been documented in every conceivable way by the joint US Air Force-Nasa mission.

Dr David Asher's predictions of the meteor storm breaking at 0210 came true and what unfolded afterwards on this unforgettable night also supports his suggestions that we flew through the edge of a filament of dust thrown off comet Tempel-Tuttle in 1899.

A century on astronomers are a major step closer to accurately forecasting this space weather with has the potential to damage satellites orbiting the Earth.

Dr Jenniskens was ecstatic: "Last night we celebrated a thousand years of the Leonids - the end of a millennium. We had fireworks, and man what fireworks they were."

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See also:

18 Nov 99 | Sci/Tech
World marvels at meteors
18 Nov 99 | Sci/Tech
Cloud spoils Leonid show
17 Nov 99 | Sci/Tech
Voyage through a comet's trail
19 Nov 98 | The Leonids 98
Picture gallery: Celestial fireworks
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