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1974 |
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Year Comet Wild 2 almost collided
with Jupiter, bringing the comet into the inner
solar system. |
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13,000 mph |
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Speed Stardust spacecraft will
pass Comet Wild 2 - six times faster than a bullet.
About 21,000 kph. |
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2:45 a.m. |
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Time (Mountain) that Stardust's
samples will re-enter Earth's atmosphere on Jan.
15, 2006. |
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30,000,000 |
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Years it takes comets on the
edge of our solar system to travel around the
sun. |
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2,380 |
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Years until Comet Hale-Bopp
will again be visible from Earth. It was last
visible in 1997. |
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76 |
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Years it takes Comet Halley
to orbit the sun. It was last visible in 1986. |
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Comets
are big chunks of ice, rock and gas. They are dirty snowballs
of leftovers from the beginning of our solar
system. Comets get their name from the Greek word "kometes"
(long hair) - a reference to their tails.
Comets are mysterious. Scientists think they might be able to tell us about the origins of our solar system.
Comets orbit the Sun like planets. Most comets orbit way out beyond the orbit of Pluto. It can take a comet hundreds or even millions of years to go once around the Sun. On Earth, it only takes 365 days. Most come from a super distant ring of debris around our solar system called the Oort Cloud.A few comets close enough for us to see from Earth. They probably come from an area around Pluto called the Kuiper Belt. When Earth passes through the tail of a comet, we see a meteor shower.
WHAT'S IT LIKE ON A COMET?
Unless you could travel way out beyond Pluto, it would
be hard to stand or land on a comet. When comets get close
to the Sun, they begin spewing gas and dust. The debris
form the head – or coma – and a tail. The
tail always points away from the Sun. The only solid part
is the nucleus in the middle.
If you did manage to land on a comet, you might end up getting blasted into space on a jet of gas and rock. Or, if your comet got too close to the Sun, it would break up completely. Gravity is so light you would feel like a feather.
Spacecraft that visit comets have to be tough. The rocks and debris in the tail can cause a lot of damage. In the next few years, scientists will use super tough spacecraft to catch pieces of a comet's tail and blast a football-field size hole in another comet to see what's inside the nucleus.
COMET CHALLENGE
As a comet approaches the sun, does its head or tail lead
the way? What about when it starts traveling away from
the Sun? Hint: The answer is on this page.
MISSIONS TO EXPLORE COMETS
Featured Mission: Stardust
Stardust will use a super light substance called Aerogel
to capture pieces of the tail of a comet and return them
to Earth.
More Missions to explore Comets:
Past
Missions
Present
Missions
Future
Missions
Source: NASA
