The Smithsonian Astrophysical Observatory (SAO) is a research institute of the Smithsonian Institution headquartered in Cambridge, Massachusetts, United States. The SAO was founded in 1890 by Samuel Pierpont Langley, the third Secretary of the Smithsonian Institution. Its mission is to “advance astrophysical knowledge and contribute to the solution of pressing astronomical problems.”
The SAO has played a leading role in American astronomy and astrophysics for over 125 years. It was instrumental in developing early aeronautical research and space science programs within the Smithsonian Institution. Today, the Observatory continues to be at the forefront of astronomical research and operates several cutting-edge telescopes and facilities.
The SAO is part of a vibrant community of astronomers and astrophysicists based in Cambridge, MA that also includes Harvard College Observatory, MIT Kavli Institute for Astrophysics and Space Research, Center for Astrophysics | Harvard & Smithsonian, as well as numerous other academic institutions and private companies. This community comprises one of the densest concentrations of astronomical expertise in the world.
The main campus of the SAO is located on a 16-acre (6.5 hectares) site near Harvard Square in Cambridge. The campus houses administrative offices, library resources, classrooms and seminar rooms, laboratory space, shops, instrument development facilities, computer systems support services, and residential apartments for staff members. The observatory also maintains several outlying facilities: Submillimeter Array on Mauna Kea in Hawaii; Infrared Telescope Facility on Mauna Kea; Fred Lawrence Whipple Observatory on Mount Hopkins in Arizona; Oak Ridge Associated Universities Radio Observatory near Knoxville Tennessee; Millstone Hill Radio Telescope west of Boston; Pisgah Astronomical Research Institute near Asheville North Carolina; Consortium for Unconventional Wisdom East Sandwich Massachusetts; Consortia for Advanced Study Centers funded by NSF at various locations around USA .
Smithsonian Astrophysical Observatory has been home to many important discoveries throughout its history. In 1946 Walter Baade working at Mt Stromlo observatory discovered that there were two types of Cepheid variables which he called ‘Population I’and ‘Population II’. Population I cepheids are young stars found near spiral arms whereas Population II cepheids are older stars found away from spiral arms or in globular clusters . This discovery allowed age datingof stellar populations which led to an estimate that our galaxy was about twice as old as previously thought . In 1960s SAO scientists using data from multiple rocket launches showed that solar wind consists mostly protons with some electrons . Also during this time it was shown that our Sun goes through 11 year cycles during which time activity such as sunspots , flares etc vary . In 1963 James E Westphal while working at Palomar observatory discovered first example quasar 3C273 which opened up study field extragalactic radio sources . Quasars are now known to be extremely luminous active galactic nuclei powered by supermassive black holes . In 1975 Alexei Filippenko while still student showed Type Ia supernova can be used standard candles i.e their intrinsic brightness allows determination distance independent manner thus providing evidence dark energy causing accelerated expansion universe first detected type Ia SN1981B observed Cerro Tololo Inter-American Chile . Later he would go discover peculiar Type Ib/c SN 2002ap considered most energetic ever seen helping understand death massive stars producing long gamma ray bursts events so powerful even obscuredby dust gas intervening galaxies observed using Swift satellite only aftergamma rays faded could visible light detected revealing shock breakout explosion ejecta slamming into circumstellar material ejected star’s winds prior explosion event caught unawares how big these things could get ! Most recently researchers have been looking high energy photons emitted AGN trying determine how matter accretes onto these monstrous objects growing ever larger swallowing anything comes too close fateful moment when entire galaxy consumed !