An observatory is a location used for observing terrestrial, marine, or celestial events. Astronomy, climatology/meteorology, geophysical, oceanography and volcanology are examples of disciplines for which observatories have been constructed. Historically, observatories were as simple as containing an astronomical sextant (for measuring the distance between stars) or Stonehenge (which has some alignments on astronomical phenomena).

The Sphinx Observatory on a mountain top in the Swiss Alps at 3,571 m (11,716 ft)

Astronomical observatories

Astronomical observatories are mainly divided into four categories: space-based, airborne, ground-based, and underground-based.

Ground-based observatories

Atacama Large Millimeter Array, Chile, at 5,058 m (16,594 ft)[1]
Paranal Observatory, Chile, home of the VLT at 2,635 m (8,645 ft)
The Mauna Kea Observatories, Hawaii, home of several of the world's largest optical telescopes at 4,205 m (13,796 ft)
Haleakala Observatory at 3,036 m (9,961 ft), Maui, Hawaii

Ground-based observatories, located on the surface of Earth, are used to make observations in the radio and visible light portions of the electromagnetic spectrum. Most optical telescopes are housed within a dome or similar structure, to protect the delicate instruments from the elements. Telescope domes have a slit or other opening in the roof that can be opened during observing, and closed when the telescope is not in use. In most cases, the entire upper portion of the telescope dome can be rotated to allow the instrument to observe different sections of the night sky. Radio telescopes usually do not have domes.

For optical telescopes, most ground-based observatories are located far from major centers of population, to avoid the effects of light pollution. The ideal locations for modern observatories are sites that have dark skies, a large percentage of clear nights per year, dry air, and are at high elevations. At high elevations, the Earth's atmosphere is thinner, thereby minimizing the effects of atmospheric turbulence and resulting in better astronomical "seeing".[2] Sites that meet the above criteria for modern observatories include the southwestern United States, Hawaii, Canary Islands, the Andes, and high mountains in Mexico such as Sierra Negra.[3] Major optical observatories include Mauna Kea Observatory and Kitt Peak National Observatory in the US, Roque de los Muchachos Observatory in Spain, and Paranal Observatory and Cerro Tololo Inter-American Observatory in Chile.

Specific research study performed in 2009 shows that the best possible location for ground-based observatory on Earth is Ridge A — a place in the central part of Eastern Antarctica.[4] This location provides the least atmospheric disturbances and best visibility.

Radio observatories

Beginning in 1930s, radio telescopes have been built for use in the field of radio astronomy to observe the Universe in the radio portion of the electromagnetic spectrum. Such an instrument, or collection of instruments, with supporting facilities such as control centres, visitor housing, data reduction centers, and/or maintenance facilities are called radio observatories. Radio observatories are similarly located far from major population centers to avoid electromagnetic interference (EMI) from radio, TV, radar, and other EMI emitting devices, but unlike optical observatories, radio observatories can be placed in valleys for further EMI shielding. Some of the world's major radio observatories include the Very Large Array in New Mexico, United States, Jodrell Bank in the UK, Arecibo in Puerto Rico, Parkes in New South Wales, Australia, and Chajnantor in Chile.

Highest astronomical observatories

Since the mid-20th century, a number of astronomical observatories have been constructed at very high altitudes, above 4,000–5,000 m (13,000–16,000 ft). The largest and most notable of these is the Mauna Kea Observatory, located near the summit of a 4,205 m (13,796 ft) volcano in Hawaiʻi. The Chacaltaya Astrophysical Observatory in Bolivia, at 5,230 m (17,160 ft), was the world's highest permanent astronomical observatory[5] from the time of its construction during the 1940s until 2009. It has now been surpassed by the new University of Tokyo Atacama Observatory,[6] an optical-infrared telescope on a remote 5,640 m (18,500 ft) mountaintop in the Atacama Desert of Chile.

Ancient Indian observatory at Delhi
"El Caracol" observatory temple at Chichen Itza, Mexico
Remains of the Maragheh observatory (under dome) at Maragheh, Iran
The Estonian Tartu Observatory starting point of the Struve Geodetic Arc.[7][8]
19th century Observatory Sydney, Australia (1872)[9]
The 1962-built Solar observatory on Lomnický peak in Slovakia[12][13]

Oldest astronomical observatories

The oldest proto-observatories, in the sense of an observation post for astronomy,[14]

The oldest true observatories, in the sense of a specialized research institute,[14][16][17] include:

Space-based observatories

The Hubble Space Telescope in Earth's orbit

Space-based observatories are telescopes or other instruments that are located in outer space, many in orbit around the Earth. Space telescopes can be used to observe astronomical objects at wavelengths of the electromagnetic spectrum that cannot penetrate the Earth's atmosphere and are thus impossible to observe using ground-based telescopes. The Earth's atmosphere is opaque to ultraviolet radiation, X-rays, and gamma rays and is partially opaque to infrared radiation so observations in these portions of the electromagnetic spectrum are best carried out from a location above the atmosphere of our planet.[25] Another advantage of space-based telescopes is that, because of their location above the Earth's atmosphere, their images are free from the effects of atmospheric turbulence that plague ground-based observations.[26] As a result, the angular resolution of space telescopes such as the Hubble Space Telescope is often much smaller than a ground-based telescope with a similar aperture. However, all these advantages do come with a price. Space telescopes are much more expensive to build than ground-based telescopes. Due to their location, space telescopes are also extremely difficult to maintain. The Hubble Space Telescope was able to be serviced by the Space Shuttles while many other space telescopes cannot be serviced at all.

Airborne observatories

SOFIA on board a Boeing 747SP

Airborne observatories have the advantage of height over ground installations, putting them above most of the Earth's atmosphere. They also have an advantage over space telescopes: The instruments can be deployed, repaired and updated much more quickly and inexpensively. The Kuiper Airborne Observatory and the Stratospheric Observatory for Infrared Astronomy use airplanes to observe in the infrared, which is absorbed by water vapor in the atmosphere. High-altitude balloons for X-ray astronomy have been used in a variety of countries.

Volcano observatories

A volcano observatory is an institution that conducts the monitoring of a volcano as well as research in order to understand the potential impacts of active volcanism. Among the best known are the Hawaiian Volcano Observatory and the Vesuvius Observatory. Mobile volcano observatories exist with the USGS VDAP (Volcano Disaster Assistance Program), to be deployed on demand. Each volcano observatory has a geographic area of responsibility it is assigned to whereby the observatory is tasked with spreading activity forecasts, analyzing potential volcanic activity threats and cooperating with communities in preparation for volcanic eruption.[27]

See also


  1. "ALMA's Solitude". Picture of the Week. ESO. Retrieved 26 December 2012.
  2. Chaisson, Eric; McMillan, Steve (2002). Astronomy Today, Fourth Edition. Prentice Hall. pp. 116–119.
  3. Chaisson, Eric; McMillan, Steve (2002). Astronomy Today, Fourth Edition. Prentice Hall. p. 119.
  4. Saunders, Will; Lawrence, Jon S.; Storey, John W. V.; Ashley, Michael C. B.; Kato, Seiji; Minnis, Patrick; Winker, David M.; Liu, Guiping & Kulesa, Craig (2009). "Where Is the Best Site on Earth? Domes A, B, C, and F, and Ridges A and B". Publications of the Astronomical Society of the Pacific. 121 (883): 976–992. arXiv:0905.4156. Bibcode:2009PASP..121..976S. doi:10.1086/605780. S2CID 11166739.
  5. Zanini, A.; Storini, M.; Saavedra, O. (2009). "Cosmic rays at High Mountain Observatories". Advances in Space Research. 44 (10): 1160–1165. Bibcode:2009AdSpR..44.1160Z. doi:10.1016/j.asr.2008.10.039.
  6. Yoshii, Yuzuru; et al. (August 11, 2009). "The 1m telescope at the Atacama Observatory has Started Scientific Operation, detecting the Hydrogen Emission Line from the Galactic Center in the Infrared Light". Press Release. School of Science, the University of Tokyo. Archived from the original on 28 May 2010. Retrieved 21 December 2009.
  7. Taavi Tuvikene, Tartu Old Observatory, 18 February 2009
  8. Tartu Observatory – Official website (English version)
  9. Official Web Site of the Sydney Observatory
  10. "One of the Oldest Observatories in South America is the Quito Astronomical Observatory". Archived from the original on 2012-01-18. Retrieved 2015-01-05.
  11. Official website of the Quito Astronomical Observatory
  12. "Slovakia's High Tatras mountains are seen from the solar observatory station on the Lomnicky Stit peak". BBC. 5 September 2014.
  13. A long time exposed picture taken by night shows Slovakia's High Tatras mountains seen from the Solar observatory station on the Lomnicky Stit peak Archived 2017-10-16 at the Wayback Machine 4 September 2014.
  14. Micheau, Francoise. "The Scientific Institutions in the Medieval Near East": 992–3. {{cite journal}}: Cite journal requires |journal= (help), in Rashed, Roshdi; Morelon, Régis (1996). Encyclopedia of the History of Arabic Science. Routledge. pp. 985–1007. ISBN 978-0-415-12410-2.
  15. "Facts about Hipparchus: astronomical observatory, as discussed in astronomical observatory:". Encyclopædia Britannica.
  16. Peter Barrett (2004), Science and Theology Since Copernicus: The Search for Understanding, p. 18, Continuum International Publishing Group, ISBN 0-567-08969-X
  17. Kennedy, Edward S. (1962). "Review: The Observatory in Islam and Its Place in the General History of the Observatory by Aydin Sayili". Isis. 53 (2): 237–239. doi:10.1086/349558.
  18. "Royal Institute and Observatory of the San Fernando Armada".
  19. "Real Observatorio de Madrid - Breve semblanza histórica". Archived from the original on 2013-07-26.
  20. "Observatorio Astronómico Nacional (Universidad Nacional de Colombia)". Archived from the original on 2008-05-11. Retrieved 2019-08-24.
  21. "On its 200th Anniversary Tartu Old Observatory Opens Doors as a Museum". www.visitestonia.com. 26 April 2011. Retrieved 26 January 2013.
  22. "National Park Service: Astronomy and Astrophysics (United States Naval Observatory)". Cr.nps.gov. 2001-11-05. Archived from the original on 2011-06-29. Retrieved 2011-11-03.
  23. Portolano, M. (2000). "John Quincy Adams's Rhetorical Crusade for Astronomy". Isis. 91 (3): 480–503. doi:10.1086/384852. JSTOR 237905. PMID 11143785. S2CID 25585014.
  24. History of astronomy at University of Helsinki 1834–1984 (in Finnish)
  25. Chaisson, Eric; McMillan, Steve (2002). Astronomy Today, Fourth Edition. Prentice Hall.
  26. "A Brief History of the Hubble Space Telescope: Why a Space Telescope?". NASA. Retrieved 2006-08-14.
  27. U.S. Geological Survey. "USGS operates five U.S. Volcano Observatories". www.usgs.gov. U.S. Geological Survey. Retrieved 8 February 2021.

Further reading

  • Aubin, David; Charlotte Bigg, and H. Otto Sibum, eds. The Heavens on Earth: Observatories and Astronomy in Nineteenth-Century Science and Culture (Duke University Press; 2010) 384 pages; Topics include astronomy as military science in Sweden, the Pulkovo Observatory in the Russia of Czar Nicholas I, and physics and the astronomical community in late 19th-century America.
  • Brunier, Serge, et al. Great Observatories of the World (2005)
  • Dick, Steven. Sky and Ocean Joined: The U.S. Naval Observatory 1830–2000 (2003)
  • Gressot Julien and Jeanneret Romain, « Determining the right time, or the establishment of a culture of astronomical precision at Neuchâtel Observatory in the mid-19th century », Journal for the History of Astronomy, 53(1), 2022, 27–48, https://doi.org/10.1177/00218286211068572
  • Leverington, David. Observatories and Telescopes of Modern Times - Ground-Based Optical and Radio Astronomy Facilities since 1945. Cambridge University Press, Cambridge 2016, ISBN 9780521899932.
  • McCray, W. Patrick. Giant Telescopes: Astronomical Ambition and the Promise of Technology (2004); focuses on the Gemini Observatory.
  • Sage, Leslie, and Gail Aschenbrenner. A Visitor's Guide to the Kitt Peak Observatories (2004)
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