Sloan Digital Sky Survey

Simply put, the Sloan Digital Sky Survey (SDSS) is the most ambitious astronomical survey ever undertaken. When completed, it will provide detailed optical images covering more than a quarter of the sky, and a 3-dimensional map of about a million galaxies and quasars. As the survey progresses, the data are released to the scientific community and the general public in annual

 

More details and pictures at: http://www.sdss.org/