This picture shows the shape and size of the orbit of Comet Wild 2. The comet's orbit is aqua. You can also see the orbits of Jupiter, Mars, and Earth. Click on image for full size (6K GIF) Image courtesy NASA/JPL.

Comet Wild 2 is named after the scientist who discovered it. Paul Wild is an astronomer from Switzerland who discovered the comet in January 1978. Wild 2 is pronounced "Vilt 2".

The comet orbits the Sun once every 6.39 years, which is a pretty short time for a comet. Some comets take more than 100 years to go around the Sun one time! The comet's orbit is not a circle. Its orbit is shaped more like an oval, which astronomers call an ellipse. When the comet is at one end of the ellipse it is as close to the Sun as it gets. When it is at the other end, it is far from the Sun. The orbit of Wild 2 brings it a bit closer to the Sun than the planet Mars. The orbit also swings the comet out beyond the orbit of Jupiter.

When we see a comet from Earth, we actually see the dust and gas the comet gives off. The dust and gas form a fuzzy head called the "coma" and tails that are thousands of kilometers (miles) long. The solid part of a comet is called the nucleus, and is in the middle of the coma. The nucleus of Wild 2 is only about five km (three miles) across.

A spacecraft named Stardust flew by Comet Wild 2 in January 2004. I took some very nice pictures of the nucleus and gathered some dust samples. It will bring the dust back to Earth so scientists can study it.