Established 1899, AAS is the major professional organization in North America for astronomers, other scientists and individuals interested in astronomy.

Was established to encourage and facilitate the observation of occultations and eclipses. It provides predictions for grazing occultations of stars by the Moon and predictions for occultations of stars by asteroids and planets, information on observing equipment and techniques, and reports to the members of observations made.

A network of volunteers have cameras focused on the sky to create a 360 degree map of the planets and stars at one time. Data is fed into a computer and filtered for atmospheric interference. Page includes details of the procedure, as well as a discussion forum.

Key activities include research and observing planets, stars, celestial phenomena and the abatement of light pollution.

Founded in 1892, is the oldest society of its kind in Australia. Its objectives are to promote the Science of Astronomy and all its branches by holding regular meetings and viewing nights, circulating current astronomical information, and encouraging popular interest in Astronomy.

Founded in 1919, has a mission to promote and safeguard the science of astronomy through international cooperation. The organization is also the internationally recognized authority for assigning designations to celestial bodies and surface features on such bodies.

A nonprofit organization that promotes exploration of the solar system and the search for extraterrestrial intelligence.

A very comprehensive collection of information useful and interesting to amateur astronomers, especially those located in Utah. Includes events, news, data and reference materials, and a weekly viewing conditions forecast. Has a special section about light pollution.