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

An observatory is a location used for observing terrestrial, marine, or celestial events. Astronomy, climatology/meteorology, geophysics, 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).


Astronomical observatories

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

Ground-based observatories

ALMA's Solitude01.jpg
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)
Mauna Kea observatory.jpg
The Mauna Kea Observatories, Hawaii, home of several of the world's largest optical telescopes at 4,205 m (13,796 ft)
Haleakala Observatory Maui (45015823284).jpg
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
Chichen Itza Observatory 2 1.jpg
"El Caracol" observatory temple at Chichen Itza, Mexico
Maragheh observatory 2.JPG
Remains of the Maragheh observatory (under dome) at Maragheh, Iran
Tartu asv2022-04 img06 Old Observatory.jpg
The Estonian Tartu Observatory starting point of the Struve Geodetic Arc. [7] [8]
SLNSW 479519 16 Observatory SH 198.jpg
19th century Observatory Sydney, Australia (1872) [9]
Observatorium Lomnicky stit 1.jpg
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 Hubble 01.jpg
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 SOFIA with open telescope doors.jpg
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

Related Research Articles

<span class="mw-page-title-main">Space telescope</span> Instrument in space to study astronomical objects

A space telescope or space observatory is a telescope in outer space used to observe astronomical objects. Suggested by Lyman Spitzer in 1946, the first operational telescopes were the American Orbiting Astronomical Observatory, OAO-2 launched in 1968, and the Soviet Orion 1 ultraviolet telescope aboard space station Salyut 1 in 1971. Space telescopes avoid the filtering and distortion (scintillation) of electromagnetic radiation which they observe, and avoid light pollution which ground-based observatories encounter. They are divided into two types: Satellites which map the entire sky, and satellites which focus on selected astronomical objects or parts of the sky and beyond. Space telescopes are distinct from Earth imaging satellites, which point toward Earth for satellite imaging, applied for weather analysis, espionage, and other types of information gathering.

Infrared astronomy is a sub-discipline of astronomy which specializes in the observation and analysis of astronomical objects using infrared (IR) radiation. The wavelength of infrared light ranges from 0.75 to 300 micrometers, and falls in between visible radiation, which ranges from 380 to 750 nanometers, and submillimeter waves.

<span class="mw-page-title-main">European Southern Observatory</span> Intergovernmental organization and observatory in Chile

The European Organisation for Astronomical Research in the Southern Hemisphere, commonly referred to as the European Southern Observatory (ESO), is an intergovernmental research organisation made up of 16 member states for ground-based astronomy. Created in 1962, ESO has provided astronomers with state-of-the-art research facilities and access to the southern sky. The organisation employs over 750 staff members and receives annual member state contributions of approximately €162 million. Its observatories are located in northern Chile.

<span class="mw-page-title-main">Hubble Deep Field</span> Multiple exposure image of deep space in the constellation Ursa Major

The Hubble Deep Field (HDF) is an image of a small region in the constellation Ursa Major, constructed from a series of observations by the Hubble Space Telescope. It covers an area about 2.6 arcminutes on a side, about one 24-millionth of the whole sky, which is equivalent in angular size to a tennis ball at a distance of 100 metres. The image was assembled from 342 separate exposures taken with the Space Telescope's Wide Field and Planetary Camera 2 over ten consecutive days between December 18 and 28, 1995.

<span class="mw-page-title-main">Observational astronomy</span> Division of astronomy

Observational astronomy is a division of astronomy that is concerned with recording data about the observable universe, in contrast with theoretical astronomy, which is mainly concerned with calculating the measurable implications of physical models. It is the practice and study of observing celestial objects with the use of telescopes and other astronomical instruments.

<span class="mw-page-title-main">Great Observatories program</span> Series of NASA satellites

NASA's series of Great Observatories satellites are four large, powerful space-based astronomical telescopes launched between 1990 and 2003. They were built with different technology to examine specific wavelength/energy regions of the electromagnetic spectrum: gamma rays, X-rays, visible and ultraviolet light, and infrared light.

<span class="mw-page-title-main">Haleakalā Observatory</span> Astronomical observatory on Maui Island, Hawaii, USA

The Haleakalā Observatory, also known as the Haleakalā High Altitude Observatory Site, is Hawaii's first astronomical research observatory. It is located on the island of Maui and is owned by the Institute for Astronomy of the University of Hawaiʻi, which operates some of the facilities on the site and leases portions to other organizations. Tenants include the Air Force Research Laboratory (AFRL) and the Las Cumbres Observatory Global Telescope Network (LCOGTN). At over 3,050 meters (10,010 ft) in altitude, the summit of Haleakalā is above one third of the Earths's troposphere and has excellent astronomical seeing conditions.

<span class="mw-page-title-main">Submillimetre astronomy</span> Astronomy with terahertz (< 1 mm)-range light

Submillimetre astronomy or submillimeter astronomy is the branch of observational astronomy that is conducted at submillimetre wavelengths of the electromagnetic spectrum. Astronomers place the submillimetre waveband between the far-infrared and microwave wavebands, typically taken to be between a few hundred micrometres and a millimetre. It is still common in submillimetre astronomy to quote wavelengths in 'microns', the old name for micrometre.

<span class="mw-page-title-main">Llano de Chajnantor Observatory</span> Observatory

Llano de Chajnantor Observatory is the name for a group of astronomical observatories located at an altitude of over 4,800 m (15,700 ft) in the Atacama Desert of northern Chile. The site is in the Antofagasta Region approximately 50 kilometres (31 mi) east of the town of San Pedro de Atacama. The exceptionally arid climate of the area is inhospitable to humans, but creates an excellent location for millimeter, submillimeter, and mid-infrared astronomy. This is because water vapour absorbs and attenuates submillimetre radiation. Llano de Chajnantor is home to the largest and most expensive astronomical telescope project in the world, the Atacama Large Millimeter Array (ALMA). Llano de Chajnantor and the surrounding area has been designated as the Chajnantor Science Reserve by the government of Chile.

<span class="mw-page-title-main">Astronomical interferometer</span> Array used for astronomical observations

An astronomical interferometer or telescope array is a set of separate telescopes, mirror segments, or radio telescope antennas that work together as a single telescope to provide higher resolution images of astronomical objects such as stars, nebulas and galaxies by means of interferometry. The advantage of this technique is that it can theoretically produce images with the angular resolution of a huge telescope with an aperture equal to the separation, called baseline, between the component telescopes. The main drawback is that it does not collect as much light as the complete instrument's mirror. Thus it is mainly useful for fine resolution of more luminous astronomical objects, such as close binary stars. Another drawback is that the maximum angular size of a detectable emission source is limited by the minimum gap between detectors in the collector array.

<span class="mw-page-title-main">Magdalena Ridge Observatory</span> American astronomical observatory

The Magdalena Ridge Observatory (MRO) is an astronomical observatory in Socorro County, New Mexico, about 32 kilometers (20 mi) west of the town of Socorro. The observatory is located in the Magdalena Mountains near the summit of South Baldy Mountain, adjacent to the Langmuir Laboratory for Atmospheric Research. Currently operational at the site is a 2.4-meter fast-tracking optical telescope, and under construction is a ten-element optical interferometer.

<span class="mw-page-title-main">Telescope</span> Optical instrument that makes distant objects appear magnified

A telescope is a device used to observe distant objects by their emission, absorption, or reflection of electromagnetic radiation. Originally meaning only an optical instrument using lenses, curved mirrors, or a combination of both to observe distant objects, the word telescope now refers to a wide range of instruments capable of detecting different regions of the electromagnetic spectrum, and in some cases other types of detectors.

<span class="mw-page-title-main">Infrared telescope</span> Telescope that uses infrared light

An infrared telescope is a telescope that uses infrared light to detect celestial bodies. Infrared light is one of several types of radiation present in the electromagnetic spectrum.

<span class="mw-page-title-main">Atmospheric window</span>

An atmospheric window is a range of wavelengths of the electromagnetic spectrum that can pass through the atmosphere of Earth. The optical, infrared and radio windows comprise the three main atmospheric windows. The windows provide direct channels for Earth's surface to receive electromagnetic energy from the Sun, and for thermal radiation from the surface to leave to space. Atmospheric windows are useful for astronomy, remote sensing, telecommunications and other science & technology applications.

<span class="mw-page-title-main">University of Tokyo Atacama Observatory</span> Observatory

The University of Tokyo Atacama Observatory (TAO) is an astronomical observatory located on the summit of Cerro Chajnantor, at an altitude of 5,640 m (18,500 ft) within a lava dome in the Atacama Desert of northern Chile. The site is located less than 5 km (3.1 mi) north-northeast of the Llano de Chajnantor Observatory, where the Atacama Large Millimeter Array (ALMA) is located, but is over 580 m (1,900 ft) higher in elevation. It is also 28 m (92 ft) higher than the Fred Young Submillimeter Telescope proposed for the same peak.


  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. 1 2 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.[ dead link ]
  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