Sky survey
A sky survey is a systematic search that photographs large areas of the sky repeatedly to find moving or changing objects.
A sky survey uses telescopes to photograph large stretches of the sky again and again. Comparing images reveals objects that move, such as asteroids and comets, or that change brightness, such as exploding stars.
Surveys are the backbone of asteroid discovery. Projects such as the Catalina Sky Survey and Pan-STARRS in the United States, ATLAS with telescopes in Hawaii, Chile and South Africa, and many others have found most of the known near-Earth asteroids. Several small asteroids that hit Earth, including 2008 TC3, were discovered by surveys only hours before impact.
The data are reported to a central clearing house, the Minor Planet Center, which calculates orbits. New space-based surveys working in infrared light, such as NASA's planned NEO Surveyor, will be especially good at spotting dark asteroids that are hard to see in visible light. The more complete the survey, the better our warning of future impacts.
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Level: Explorer Ages 10 and up