The 658,859 known asteroids in the solar system are small bodies left over from its formation. Most of the known asteroids orbit in the Main Belt between Mars and Jupiter. Asteroids (the name means “starlike bodies”) can be as small as a few meters across, or as large as an asteroid like Ceres, almost 1,000 km in diameter (or about 1/12 of Earth). They vary in color from darker than charcoal to the color of freshly broken rock. Typically, asteroid orbits are more inclined (tipped) and more eccentric than any of the planets.
 
The study of the asteroids helps us understand how planets and the basis for life form and evolve. Since no significant geological processes have taken place on these small bodies, the asteroids preserve a history of the Solar System in a way that the planets do not. These minor bodies contain relics of the conditions of the early Solar System.
 
Scientists also like to keep tabs on near-Earth asteroids. In 1994, Comet Shoemaker-Levy 9 slammed into Jupiter, leaving scars larger than the earth on the giant planet. We have evidence of other impacts on our planet, even within the last 100 years. As the events of February 15th, 2013 show in videos and photos from Chelyabinsk, Russia, occasionally one of the asteroids will impact our planet. Improving the detection efficiency of existing surveys is an excellent way to increase the number of asteroid detections.
 
Your goal in Asteroid Zoo is to identify moving dots in images provided by the Catalina Sky Survey (CSS), a site funded by NASA to find asteroids, in particular all the Near Earth Objects with a radius larger than 100 meters. These dots could be asteroids or some other celestial objects, which you would classify as “artifacts.”