Satellite Watching

Also called satellite spotting, a hobby of observing and tracking artificial satellites orbiting Earth, made possible because satellites in low orbit often reflect sunlight visibly as they cross the sky, especially around twilight; practitioners are called watchers, trackers, spotters or observers. The hobby began with Operation Moonwatch, launched by the Smithsonian Astrophysical Observatory in 1956 to enlist amateur astronomers in tracking the Soviet Sputnik satellites, modeled on the Ground Observer Corps of the Second World War, and remained important until professional tracking stations took over in 1958, with the program itself continuing until 1975 even as individual watchers kept tracking on their own. Digital tools transformed the hobby from the 2000s onward, with planetarium and satellite-tracking software followed by augmented-reality apps in the 2010s, and today's satellite watchers use digital cameras and astrometry software to calculate orbits, cooperating through networks such as the SeeSat-L mailing list to track intelligence-gathering satellites.