The Sunspot Solar Observatory (SSO) is an
astronomical
Astronomy () is a natural science that studies celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and evolution. Objects of interest include planets, moons, stars, nebulae, galaxies, ...
observatory
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. H ...
designed for the study of the
Sun
The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared rad ...
. The observatory is operated by
New Mexico State University
New Mexico State University (NMSU or NM State) is a public land-grant research university based primarily in Las Cruces, New Mexico. Founded in 1888, it is the oldest public institution of higher education in New Mexico and one of the stat ...
(NMSU) and the U.S.
National Solar Observatory
The National Solar Observatory (NSO) is a United States public research institute to advance the knowledge of the physics of the Sun. NSO studies the Sun both as an astronomical object and as the dominant external influence on Earth.
NSO is hea ...
(NSO). It is split between operations at the telescope facility at
Sunspot,
New Mexico
)
, population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano)
, seat = Santa Fe, New Mexico, Santa Fe
, LargestCity = Albuquerque, New Mexico, Albuquerque
, LargestMetro = Albuquerque metropolitan area, Tiguex
, Offi ...
, and data and management at the Department of Astronomy at
New Mexico State University
New Mexico State University (NMSU or NM State) is a public land-grant research university based primarily in Las Cruces, New Mexico. Founded in 1888, it is the oldest public institution of higher education in New Mexico and one of the stat ...
. The Sunspot telescope facility is in the
Sacramento Mountains
The Sacramento Mountains are a mountain range in the south-central part of the U.S. state of New Mexico, lying just east of Alamogordo in Otero County (small portions of the range lie in Lincoln County and Chaves County). From north to south ...
, approximately south of
Cloudcroft
Cloudcroft is a village in Otero County, New Mexico, United States, and is located within the Lincoln National Forest. The population was 674 at the 2010 census. Despite being located in an otherwise arid region, its high elevation (; one of ...
. Access to the facility telescopes and grounds are open for to the public for guided tours. It is funded by the National Science Foundation in partnership with the state of New Mexico.
General information

The Sunspot telescope facility is located in
Sunspot, New Mexico
Sunspot is an unincorporated community in the Sacramento Mountains in the Lincoln National Forest in Otero County, New Mexico, United States, about south of Cloudcroft. Its elevation is . The Sunspot Solar Observatory and Apache Point Observa ...
, and is part of the
Lincoln National Forest
Lincoln National Forest is a unit of the U.S. Forest Service located in southern New Mexico. Established by Presidential Proclamation in 1902 as the Lincoln Forest Reserve, the forest begins near the Texas border and contains lands in parts of ...
on the western edge of the
Sacramento Mountains
The Sacramento Mountains are a mountain range in the south-central part of the U.S. state of New Mexico, lying just east of Alamogordo in Otero County (small portions of the range lie in Lincoln County and Chaves County). From north to south ...
. The ~ area is located on
National Forest Service
The United States Forest Service (USFS) is an agency of the U.S. Department of Agriculture that administers the nation's 154 national forests and 20 national grasslands. The Forest Service manages of land. Major divisions of the agency in ...
lands, managed by the
U.S. Department of Agriculture
The United States Department of Agriculture (USDA) is the federal executive department responsible for developing and executing federal laws related to farming, forestry, rural economic development, and food. It aims to meet the needs of com ...
,
U.S. Forest Service
The United States Forest Service (USFS) is an agency of the United States Department of Agriculture, U.S. Department of Agriculture that administers the nation's 154 United States National Forest, national forests and 20 United States Nationa ...
(USFS), Lincoln National Forest, and the
Sacramento Ranger District
)
, image_map = Sacramento County California Incorporated and Unincorporated areas Sacramento Highlighted.svg
, mapsize = 250x200px
, map_caption = Location within Sacramento ...
. Established by the U.S. Air Force (USAF) via a Memorandum of Agreement with the USFS in 1950, the facility was transferred to NSF in 1976. NSF and the USFS executed a land use agreement (1980) to formalize this transfer and the continued use of the land for the NSO. It was later known as the
Sacramento Peak Observatory, and as one site of the
National Solar Observatory
The National Solar Observatory (NSO) is a United States public research institute to advance the knowledge of the physics of the Sun. NSO studies the Sun both as an astronomical object and as the dominant external influence on Earth.
NSO is hea ...
(NSO). In 2018, all scientific research and public outreach at the telescope facility was taken over by the Sunspot Solar Observatory and AURA remain the operator of infrastructure on the site, including maintenance.
Sunspot Solar Observatory is a global consortium that currently consists of personnel both in
Sunspot, New Mexico
Sunspot is an unincorporated community in the Sacramento Mountains in the Lincoln National Forest in Otero County, New Mexico, United States, about south of Cloudcroft. Its elevation is . The Sunspot Solar Observatory and Apache Point Observa ...
, at
New Mexico State University
New Mexico State University (NMSU or NM State) is a public land-grant research university based primarily in Las Cruces, New Mexico. Founded in 1888, it is the oldest public institution of higher education in New Mexico and one of the stat ...
in
Las Cruces, New Mexico
Las Cruces (; "the crosses") is the second-largest city in the U.S. state of New Mexico and the seat of Doña Ana County. As of the 2020 census the population was 111,385. Las Cruces is the largest city in both Doña Ana County and southern Ne ...
, and other institutes across the world
Telescopes

The flagship telescope at the Sacramento Peak Observatory is the
Richard B. Dunn Solar Telescope (DST), previously known as the Vacuum Tower Telescope.
In addition to the DST, Sunspot Solar Observatory hosts four other telescopes.
The John W. Evans Solar Facility (originally built 1952) hosted instruments for the
High Altitude Observatory
The High Altitude Observatory (HAO) conducts research and provides support and facilities for the solar-terrestrial physics research community in the areas of solar and heliospheric physics, and the effects of solar variability on the Earth's m ...
and the
Air Force Research Lab
The Air Force Research Laboratory (AFRL) is a scientific research organization operated by the United States Air Force Materiel Command dedicated to leading the discovery, development, and integration of aerospace warfighting technologies, pl ...
and until 2009 obtained daily observations of million degree coronal emission that were used to predict the onset of the following
solar cycle
The solar cycle, also known as the solar magnetic activity cycle, sunspot cycle, or Schwabe cycle, is a nearly periodic 11-year change in the Sun's activity measured in terms of variations in the number of observed sunspots on the Sun's surfa ...
.
The other two Dome buildings (Hilltop Dome 1963, Grain Bin Dome 1950) are not used for research.
An Antarctic Mount telescope is situated beside the Visitors' Center on site and provides a light feed into the Visitors' Center. As the name suggests, this telescope was previously deployed in the Antarctic.
Visitor Center

The Sunspot Astronomy and Visitor Center provides an interactive astronomical experience through activities, displays, and informational exhibits. The Center is operated by
New Mexico State University
New Mexico State University (NMSU or NM State) is a public land-grant research university based primarily in Las Cruces, New Mexico. Founded in 1888, it is the oldest public institution of higher education in New Mexico and one of the stat ...
through support from the state of New Mexico and provides guided tours of the site and the telescope for the public on Saturday and Sunday. Self-guided tours are available during other times. The Visitor Center contains exhibits from the
Dunn Solar Telescope, the
Apache Point Observatory
The Apache Point Observatory (APO; obs. code: 705) is an astronomical observatory located in the Sacramento Mountains in Sunspot, New Mexico, United States, approximately south of Cloudcroft. The observatory is operated by New Mexico State Un ...
, and the Lincoln National Forest.
History
The origins of
Sunspot as a Solar Observatory date back to the sudden increased interest of
solar physics
Solar physics is the branch of astrophysics that specializes in the study of the Sun. It deals with detailed measurements that are possible only for our closest star. It intersects with many disciplines of pure physics, astrophysics, and com ...
to the US military during the
Second World War
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the World War II by country, vast majority of the world's countries—including all of the great power ...
. In 1940, the
High Altitude Observatory
The High Altitude Observatory (HAO) conducts research and provides support and facilities for the solar-terrestrial physics research community in the areas of solar and heliospheric physics, and the effects of solar variability on the Earth's m ...
(HAO) was established in 1940 in Climax, Colorado, by Walter Orr Roberts and Donald Menzel. It was associated with both Harvard College Observatory and the University of Colorado and was incorporated in 1946. At the time it was the world's highest permanent observatory for astronomy, at an elevation of over 11,000 feet, and was designed purely for studying the Sun. Roberts worked with the Bureau of Standards, "forecasting radio conditions on the basis of solar observations".
Such studies of the upper atmosphere were critical for predicting conditions for radio communication, guided missiles, and supersonic aircraft and, as a result, solar observations "became essential to the war effort". Suddenly the field of
solar astronomy
The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared rad ...
became an appealing goal for both astronomers and the military.
The Sacramento Peak Observatory was conceived as a complementary telescope to the existing facilities in Climax, as Roberts had realized that "there were long periods of cloudiness, especially during the winter, when it was not possible to make observations",
and hence a second dedicated solar observatory should be established. The practical applications for solar research, as discovered by the military during World War II, regarding the impact solar activity had on radio communication spurred the US Congress to provide for a military-funded observatory. It became an important mission of the USAF to establish a solar observatory and "after the war, when the Air Force recognized the need to organize its own long-range program of solar studies, it quite naturally turned for specialized assistance to the recently formed High Altitude Observatory (HAO)".
In September 1947, the USAF issued a contract to HAO and Harvard University to conduct a survey and thereby identify an appropriate site for a new solar observatory and to determine which instruments to install at the new site.
Any seasonal cloud cover at the new site needed to arrive in the opposite season to that at Climax, in order to then provide for year-round coverage of the Sun. Similar to Climax, the atmosphere above the new site should be exceptionally free from haze and dust in order to permit for the best possible observing. Roberts and Menzel examined the White Sands Proving Ground (an area used as a research rocket firing range near Holloman Air Force Base in Alamogordo, New Mexico). They "concluded that the section of the Sacramento Mountains in which Sacramento Peak is located would be especially promising for a solar research site. Further inquiries and inspection tended to confirm this initial reaction".
Holloman Air Force Base could be used to supply the equipment and any supplies. Sacramento Peak was, at 9200 feet was also low enough to be more accessible to researchers than Climax at 11,000 feet and the thickly forested setting blocked interference from rising air currents up the mountain.
A small crew of five made the initial camp at the Sunspot site. This crew included Roberts, John "Jack" W. Evans (a student of Menzel's), and Rudy Cook (who had worked with Robert in Climax).
Cook's companions soon returned home, leaving Cook and his dog Rocky to man the site. By the end of 1947, Menzel and Roberts made the recommendation that Sacramento Peak be chosen as the solar research site for USAF. By April 1948, the Committee on Geophysical Sciences (then within the War Department's Research and Development Board) formally accepted this recommendation and a contract was written, mandating the Air Force to complete the observatory. The specifics of the contract called for "the preparation of detailed plans for an integrated solar research facility, which would combine observational, analytical, and data-reduction activities, all on a larger scale than at any comparable observatory; design, development, and fabrication of the required optical device; and concurrently, theoretical studies of solar structure and characteristics"
Views from Sunspot
On the western side of the Sacramento peak, there are wide open views of
Apache Point Observatory
The Apache Point Observatory (APO; obs. code: 705) is an astronomical observatory located in the Sacramento Mountains in Sunspot, New Mexico, United States, approximately south of Cloudcroft. The observatory is operated by New Mexico State Un ...
and
Sloan Digital Sky Survey telescopes. From the overlook beside the telescope,
White Sands National Park
White Sands National Park is an American national park located in the state of New Mexico and completely surrounded by the White Sands Missile Range. The park covers in the Tularosa Basin, including the southern 41% of a field of white sand d ...
stands out as gypsum white
against the sandy background of the desert. On a clear day it is possible to see all the way south to the cities of
El Paso, Texas
El Paso (; "the pass") is a city in and the seat of El Paso County in the western corner of the U.S. state of Texas. The 2020 population of the city from the U.S. Census Bureau was 678,815, making it the 23rd-largest city in the U.S., the ...
, and
Ciudad Juárez, Mexico, and all the way north to the
Trinity test site. The overlook can also be used for viewing rocket launches from
White Sands Missile Range
White Sands Missile Range (WSMR) is a United States Army military testing area and firing range located in the US state of New Mexico. The range was originally established as the White Sands Proving Ground on 9July 1945. White Sands National P ...
.
Gallery
File:DST at night.jpg, DST at night
File:SDSS from Sunspot.jpg, SDSS from Sunspot
See also
*
List of astronomical observatories
This is a list of astronomical observatories ordered by name, along with initial dates of operation (where an accurate date is available) and location. The list also includes a final year of operation for many observatories that are no longer in ...
*
List of solar telescopes
This is a list of solar telescopes built in various countries around the world. A solar telescope is a specialized telescope that is used to observe the Sun.
This list contains ground-based professional observatory telescopes at optical wavelength ...
References
External links
Dunn Solar Telescope websiteUSDA websiteNewMexico.org website
{{authority control
Solar telescopes
Solar observatories
Optical telescopes
Astronomical observatories in New Mexico
Buildings and structures in Otero County, New Mexico
1958 establishments in New Mexico