American Astronomical Society (AAS)
Established 1899, AAS is the major professional organization in North America for astronomers, other scientists and individuals interested in astronomy.
http://www.aas.org
Astronomical Applications Department, U.S. Naval Observatory
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Computes the position, brightness, and other observable characteristics of celestial bodies, as well as the circumstances of astronomical phenomena. Includes information on calendars and related topics.
http://aa.usno.navy.mil/
NASA Space Science and Astronomy News
What's new in NASA's space science programs.
http://www.nasa.gov/news/highlights/
Space
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Offers space, astronomy and technology content, including information, education, entertainment and business news.
http://www.space.com
Time and Date
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Lots of time and date related information, such as yearly and monthly calendars, counters, countdown, and the world clock which shows the current time in cities all over the world.
http://www.timeanddate.com/