Amateur astronomers seeking new challenges, find that spotting faint, rapidly moving satellites, such as the tiny Vanguard 1 (America's second satellite), are comparable to spotting a distant galaxy. Tracking down a newly launched spy satellite in a secret orbit, tests analytical as well as observational skill. Observing the International Space Station transit the sun, moon or one of the planets, requires planning, perseverance, and often a bit of luck.
Positional observers precisely measure the time and position of satellites as they cross the sky. During the first 30 years of the space age, geophysicists used such hobbyist measurements alongside those of radars and telescopic cameras, to analyze small changes in satellite orbits - called perturbations - to reveal details of Earth's upper atmosphere and gravity field. Today, positional observers contribute to public knowledge by finding, tracking and publishing the orbits of satellites in secret orbits.
Flash observers, measure the period of rotation of spinning satellites, leading to a better understanding of the near Earth environment, especially its magnetic field.
Space enthusiasts find that satellite observation leads naturally into such diverse fields as orbital mechanics, computer programming, rocket propulsion, mathematics, physics, applications of satellites, and government space policy.
This web site provides information on all facets of visual satellite observation: