Computer monitors track observations at the Arecibo Radio Observatory.The Arecibo Observatory is a radio telescope just over 1,000 feet (305 m) across, the largest single radio telescope. The main metal collecting dish sits fixed a hemispherical karst sinkhole. The window looks out over the dish, and the spherical reflector (needed because the dish is fixed in place) can be seen hanging over the dish through the window. The observatory is the primary location of the National Astronomy and Ionosp