Tails of Wonder!

Tails of Wonder!

Help the Stardust spacecraft capture comet dust and bring it back to Earth!

Test your comet IQ and help Stardust capture samples from Comet Wild 2. Each time you answer a question correctly, Stardust will move a little closer to the comet. If you get 8 out of 10 correct, Stardust will capture samples of the comet and bring them home to Earth.

If you don't know an answer, keep reading here!

Stardust will capture comet dust and bring it home to Earth.

Stardust is the first space mission to capture dust from a comet and return it to Earth. Stardust was launched on February 7, 1999. On January 2, 2004, Stardust met up with Comet Wild 2 (pronounced "Vilt 2"). Before it got there, the spacecraft had to make two trips around the Sun. Then it captured particles of dust using some very weird stuff called aerogel.

Aerogel looks like frozen smoke. It is so light and wispy you can see right through it. It is the lightest known solid material. The comet particles were trapped gently inside the aerogel and stored safely for the trip home. See more pictures of aerogel.

Aerogel is the lightest known solid material.

Stardust made one more trip around the Sun to catch up with Earth again. The samples inside the aerogel, stored in a special reentry capsule, parachuted safely to Earth on January 15, 2006.

Why sample a comet?

But why take all this time and trouble to bring home comet samples?

Comets are believed to be a very old part of our solar system. They are made of the leftover materials that didn't become part of the Sun, the planets, or the moons. If we knew more about comets, we would know more about how our solar system formed over four billion years ago!

The nucleus, or solid part of a comet, is usually less than 10 kilometers (about 6 miles) across. The nucleus is like a dirty snowball. Nobody knows for sure what any comet is like inside. Maybe they are not all similar.

Comets seem to contain a lot of ice, some rocks and dust, and some gas. As they get closer to the Sun and start to heat up, some of their materials starts to boil off. This material forms a cloud around the nucleus. The cloud is called the coma and may be hundred of thousands of kilometers in diameter. And trailing out for oftentimes millions of kilometers are the comet's tails.

Why do comets have tails?

Most comets have two tails. The tails appear as the comet approaches the Sun. Sunlight pushes on things, but very gently. Because the comet dust particles are so small, they are pushed away from the Sun into a long tail. Another tail is made of electrically charged molecules of gas (called ions). Very rarely a comet will have a third tail made of sodium, which we usually don't see with our unaided eyes.

Comet's tails always point away from Sun.

In the early time of our solar system, Earth was often hit by comets. Scientists believe comets may have contributed some of the water for our oceans or even some of the molecules from which life eventually evolved.

Some believe it may have been a comet hitting Earth that caused the dinosaurs to become extinct.

The Stardust mission, as well as other comet missions NASA has planned, will teach us much more about these fascinating solar system objects.

Read about the discoveries that another comet mission has made.

Cartoon of two dinosaurs looking up at a comet falling from the sky. One is saying 'Uh-oh!'
article last updated July 17, 2012
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