In 1999 NASA launched a mission to collect and bring back samples from a comet.
Let next Monday be the day when statesmen take the first stop towards a comet-free future.
What they don't think about is - what are the chances of a comet hitting anything, ever?
Many such quartets blaze like a comet across the sky and then disappear before you can turn your head.
Which is why, after a comet struck Jupiter in 1994, NASA decided to launch a research programme into Near-Earth Objects.
Its atmosphere is escaping like a comet but on a planetary scale.
What's the view like from inside a nebula, or a comet's tail?
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If such a comet were the size of Hale-Bopp, Eichler says, the resulting solar flare would by far be the largest ever observed.
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Thereabouts, on clear nights, they will see a comet known as Ikeya-Zhang, after its co-discoverers, Kaoru Ikeya, of Japan, and Zhang Daqing, of China.
On July 4th, the spacecraft Deep Impact will launch a projectile at Tempel 1, a comet NASA has been watching for a few years.
As a comet gets closer to the sun, the sun's heat causes these elements to melt, spewing out dust and gas in a brilliant tail.
The material that is burning up in Earth's atmosphere during the Quadrantids likely comes from a comet that broke into fragments centuries ago, NASA says.
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Hanwell Snr came to Hanwell like a comet, at long intervals.
Stardust is an ambitious but low-cost mission to capture the first samples from a comet, as well as grains of interstellar dust, and return them to Earth.
But it's a comet that you need binoculars or a small telescope to see now, for minutes or even for an hour or two after this collision.
Europe already has a major mission en route to Jupiter's orbit - the Rosetta mission, which will chase down a comet and put a lander on its surface.
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Appropriately for someone who is best known for having discovered a comet, Halley used tiny comet-like marks to indicate wind direction, an idea that did not catch on.
Only when a comet arriving from the Oort cloud has its orbit tweaked by a close encounter with a planet does it settle into a more regular existence.
Sunday's eye-catching event occurred at the height of the annual Lyrid meteor shower, which happens every April as Earth plows through the dust and debris trailing a comet called Thatcher.
The first is that the asteroid is really a ball of ice, like the nucleus of a comet, and that the minerals which the spectroscope detected are only a coating.
There, he collapses backward as Stravinsky's final, bleating note cues the escape from within the proscenium space of a silky wisp of pure-white fabric, sending it like a comet into the auditorium ceiling.
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His figures were roughly a centimetre tall, most made with two deliberate strokes of the brush, and allowed to fade away as his paint ran out, like the trailing tail of a comet.
Luckily, Stardust, a sister mission to Genesis which gathered bits of a comet in the same way, and is due back in 2006, seems to have its switches in the right way up.
He had spent the day working at a Comet store in Torquay, picked up his girlfriend in Paignton, drove to Exeter to pick up his belongings and then set off for Cornwall about 7.30pm.
Elegantly echoing the activities of these early, ground-breaking astronomers, what we now refer to as "crowd-sourcing" has recently been shown to be able to determine the trajectory of a comet as spectacular as the one observed in 1680.
In 2004, the probe called Stardust swung by a comet called Wild 2, stuck out sort of a big catcher's mitt--I think it looks more like a tennis racket--and hopefully it picked up some of the particles thrown off by the comet.
It's never happened before that we've fired a very large bullet that's made largely of copper and aluminum, the size of a washing machine, at a comet that's about--the comet's nucleus is about four or five miles across--to make a big crater.
The severity of the laboratory test was equivalent to an oblique collision with the rocky surface of the Earth - a comet coming in at an angle of less than 25 degrees from the horizon, rather than head on (perpendicular to the Earth's surface).
Now that it seems likely a comet has drawn a sharp line of charcoal between the two cultures, careful measurements should be able to show whether North America was, for a few centuries after the impact, as bereft of people as it has since been of mammoths.
One answer might be that the two impacts were, in effect, simultaneous that the objects which created Shiva and Chicxulub were the daughters of a comet that had broken up in space and hit the Earth a few hours apart, as the pieces of comet Shoemaker-Levy 9 hit Jupiter in 1994.
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