Web Link
  Link   HM Nautical Almanac Office
The Office produces astronomical data suitable for a wide range of users, including professional and amateur astronomers, mariners, aviators, surveyors, the Armed Forces, the Police, lawyers, religious groups, architects, schools, diary and calendar
  Link   SETI Institute
Our mission is to explore, understand and explain the origin, nature and prevalence of life in the universe.
  Link   International Dark Sky Association
Dedicated to sound lighting practices and preserving dark skies.
  Link   The American Astronomical Society
The American Astronomical Society (AAS), established 1899, is the major organization of professional astronomers in North America
  Link   International Year of Astronomy 2009
The vision of the International Year of Astronomy 2009 is to help the citizens of the world rediscover their place in the Universe through the day- and night time sky, and thereby engage a personal sense of wonder and discovery.
  Link   International Astronomical Union
The International Astronomical Union (IAU) was founded in 1919. Its mission is to promote and safeguard the science of astronomy in all its aspects through international cooperation.
  Link   Astrnomical Society of the Pacific
Website of the ASP.