Astronomy Day is cosponsored by 14 astronomical and astronomy education originations. They are:
ASTRONOMICAL LEAGUE www.astroleague.org
The Astronomical League bylaws were ratified in 1941 but not incorporated until 1947 because of WWII. It is a nonprofit federation of more than 200 amateur astronomy clubs and 19,000 individuals across the United States. Individual and international membership in the Astronomical League is also possible.
ASTRONOMICAL SOCIETY OF THE PACIFIC http://www.astrosociety.org/
The Astronomical Society of the Pacific was founded in 1889 and has become the largest general astronomy society in the world, with members from over 70 nations. The Society offers programs and activities for each unique part of our membership. The ASP has also developed into the recognized leader in the field of astronomy education. Our free teachers' newsletter, The Universe in the Classroom, is posted on the web.
THE ROYAL ASTRONOMICAL SOCIETY OF CANADA http://www.rasc.ca/
The beginnings of "The Royal Astronomical Society of Canada" (RASC) go back to the middle of the nineteenth century. The Society was incorporated within the province of Ontario in 1890, received its Royal Charter from King Edward VII in 1903, and was federally incorporated in 1968. Today there are 27 Centres across Canada with over 4900 members worldwide.
AMERICAN ASTRONOMICAL SOCIETY http://www.aas.org
The American Astronomical Society was established in 1899, and is the major organization of professional astronomers in North America. The basic objective of the AAS is to promote the advancement of astronomy and closely related branches of science. Current membership is approximately 6500. Members also include physicists, mathematicians, geologists, engineers and others whose research interests lie within the broad spectrum of subjects now comprising contemporary astronomy.
ASTRONOMICAL ASSOCIATION OF NORTHERN CALIFORNIA
AANC is an association of astronomy clubs in the northern California area and the founding organization of Astronomy Day.
WESTERN AMATEUR ASTRONOMERS http://www.waa.av.org/
The Western Amateur Astronomers was formed as a regional group of local Astronomy Clubs to combine their efforts to establish a better understanding of the field of Astronomy.
AMERICAN ASSOCIATION OF PHYSICS TEACHERS http://www.aapt.org/
AAPT was established in 1930 with the fundamental goal of ensuring the "dissemination of knowledge of physics, particularly by way of teaching." In addition to helping members learn more about traditional teaching methods, AAPT promotes new teaching methods and use of modern technology to entice students with the wonders of science.
ASSOCIATION OF LUNAR AND PLANETARY OBSERVERS http://alpo-astronomy.org/
The Association of Lunar and Planetary Observers (A.L.P.O.) was founded by Walter H. Haas in 1947, and incorporated in 1990, as a medium for advancing and conducting astronomical work by both professional and amateur astronomers who share an interest in Solar System observations. Our goals are to stimulate, coordinate, and generally promote the study of these bodies using methods and instruments that are available within the communities of both amateur and professional astronomers.
AMERICAN METEOR SOCIETY http://www.amsmeteors.org/
The American Meteor Society, Ltd., a non-profit scientific organization established to encourage and support the research activities of both amateur and professional astronomers who are interested in the fascinating field of Meteor Astronomy. Our affiliates observe, monitor, collect data on, study, and report on meteors, meteor showers, meteoric fireballs, and related meteoric phenomena.
AMERICAN ASSOCIATION OF VARIABLE STAR OBSERVERS http://www.aavso.org/
The AAVSO was founded in 1911 at Harvard College Observatory to coordinate variable star observations made largely by amateur astronomers. In 1954, the AAVSO became an independent, private research organization. Today it has members in more than 40 countries, with over 10 million observations to date. It is the world's largest association of variable star observers.
THE PLANETARY SOCIETY http://planetary.org/index.html
The Planetary Society is the largest nonprofit, nongovernmental, space advocacy group on Earth. Funded entirely by individuals, the Society helps to make space exploration happen in many different ways.
NATIONAL SPACE SOCIETY http://www.nss.org/
The National Space Society (NSS) is an independent, international, educational, grassroots nonprofit 501(c)3 organization dedicated to the creation of a spacefaring civilization. The NSS has more than 22,000 members, and 75 chapters in the United States, Canada, Mexico, Australia, Germany, Ireland, and the United Kingdom. The NSS, founded in 1974 by Wernher von Braun, is widely acknowledged as the preeminent citizen's voice on space.
INTERNATIONAL PLANETARIUM SOCIETY http://www.ips-planetarium.org/
The International Planetarium Society (IPS) is the largest organization of professional planetarians in the world. It is made up of members from almost every continent, and has nearly 20 smaller affiliate organizations associated with it.
ASSOCIATION OF ASTRONOMY EDUCATORS
The Association of Astronomy Educators, an affiliate of the National Science Teachers Association, serves its members by disseminating information and opportunities to improve the teaching and learning in astronomy and space science and by providing a forum for its members to share resources and teaching strategies at national conferences of the NSTA. You can join their mailing list by going to http://groups.yahoo.com/group/astroed_news/
In addition, the INTERNATIONAL ASTRONOMICAL UNION http://www.iau.org/, a world wide group of professional astronomers, has endorsed the concept of Astronomy Day.