Stardust is coming home after seven years in space. Image Credit: NASAAfter almost seven years and billions of miles of travel through space, the Stardust spacecraft is about to come home. When it passes by Earth on Jan. 15, 2006, it will bring with it an incredible souvenir of its trip -- samples of comet and interstellar dust.
Stardust took this picture as it neared Wild 2 two years ago. Image Credit: NASAScientists believe that some comets are older than the planets of our solar system. Because their orbits carry them so far from the sun, comets spend much of their existence in extreme cold. This preserves them much as they were when they first formed, leaving them in a pristine condition that is ideal for research. When they approach the sun, they heat up. Dust and gas start to boil off, forming the area known as the coma. The dust Stardust collected was from the coma of Wild 2. Scientists believe the dust may be the oldest material ever brought back to Earth.