A solar telescope is a special purpose
telescope
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 ...
used to observe 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 radi ...
. Solar telescopes usually detect light with wavelengths in, or not far outside, the
visible spectrum
The visible spectrum is the portion of the electromagnetic spectrum that is visual perception, visible to the human eye. Electromagnetic radiation in this range of wavelengths is called ''visible light'' or simply light. A typical human eye wil ...
. Obsolete names for Sun telescopes include heliograph and photoheliograph.
Professional solar telescopes
Solar telescopes need optics large enough to achieve the best possible
diffraction limit
The resolution of an optical imaging system a microscope, telescope, or camera can be limited by factors such as imperfections in the lenses or misalignment. However, there is a principal limit to the resolution of any optical system, due to t ...
but less so for the associated light-collecting power of other astronomical telescopes. However, recently newer narrower
filters
Filter, filtering or filters may refer to:
Science and technology
Computing
* Filter (higher-order function), in functional programming
* Filter (software), a computer program to process a data stream
* Filter (video), a software component tha ...
and higher framerates have also driven solar telescopes towards photon-starved operations. Both the
Daniel K. Inouye Solar Telescope
The Daniel K. Inouye Solar Telescope (DKIST) is a scientific facility for studies of the sun at Haleakala Observatory on the Hawaiian island of Maui. Known as the Advanced Technology Solar Telescope (ATST) until 2013, it was named after Daniel K. ...
as well as the proposed
European Solar Telescope (EST) have larger apertures not only to increase the resolution, but also to increase the light-collecting power.
Because solar telescopes operate during the day, seeing is generally worse than for night-time telescopes, because the ground around the telescope is heated which causes
turbulence
In fluid dynamics, turbulence or turbulent flow is fluid motion characterized by chaotic changes in pressure and flow velocity. It is in contrast to a laminar flow, which occurs when a fluid flows in parallel layers, with no disruption between ...
and degrades the resolution. To alleviate this, solar telescopes are usually built on towers and the structures are painted white. The
Dutch Open Telescope is built on an open framework to allow the wind to pass through the complete structure and provide cooling around the telescope's main mirror.
Another solar telescope-specific problem is the heat generated by the tightly-focused sunlight. For this reason, a
heat stop is an integral part of the design of solar telescopes. For the
Daniel K. Inouye Solar Telescope
The Daniel K. Inouye Solar Telescope (DKIST) is a scientific facility for studies of the sun at Haleakala Observatory on the Hawaiian island of Maui. Known as the Advanced Technology Solar Telescope (ATST) until 2013, it was named after Daniel K. ...
, the heat load is 2.5 MW/m
2, with peak powers of 11.4 kW. The goal of such a heat stop is not only to survive this heat load, but also to remain cool enough not to induce any additional turbulence inside the telescope's dome.
Professional solar observatories may have main optical elements with very long
focal lengths (although not always,
Dutch Open Telescope) and light paths operating in a
vacuum
A vacuum is a space devoid of matter. The word is derived from the Latin adjective ''vacuus'' for "vacant" or "void". An approximation to such vacuum is a region with a gaseous pressure much less than atmospheric pressure. Physicists often dis ...
or
helium
Helium (from el, ἥλιος, helios, lit=sun) is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table. ...
to eliminate air motion due to
convection
Convection is single or multiphase fluid flow that occurs spontaneously due to the combined effects of material property heterogeneity and body forces on a fluid, most commonly density and gravity (see buoyancy). When the cause of the convec ...
inside the telescope. However, this is not possible for apertures over 1 meter, at which the pressure difference at the entrance window of the vacuum tube becomes too large. Therefore, the
Daniel K. Inouye Solar Telescope
The Daniel K. Inouye Solar Telescope (DKIST) is a scientific facility for studies of the sun at Haleakala Observatory on the Hawaiian island of Maui. Known as the Advanced Technology Solar Telescope (ATST) until 2013, it was named after Daniel K. ...
and the
EST have active cooling of the dome to minimize the temperature difference between the air inside and outside the telescope.
Due to the suns narrow path across the sky, some solar telescopes are fixed in position (and are sometimes buried underground), with the only moving part being a
heliostat
A heliostat (from ''helios'', the Greek word for ''sun'', and ''stat'', as in stationary) is a device that includes a mirror, usually a plane mirror, which turns so as to keep reflecting sunlight toward a predetermined target, compensating ...
to track the Sun. One example of this is the
McMath-Pierce Solar Telescope.
Selected solar telescopes
* The
Einstein Tower
The Einstein Tower (German: ''Einsteinturm'') is an astrophysical observatory in the Albert Einstein Science Park in Potsdam, Germany built by architect Erich Mendelsohn. It was built on the summit of the Potsdam '' Telegraphenberg'' to house ...
(''Einsteinturm'') became operational in 1924
*
McMath-Pierce Solar Telescope (1.6 m diameter, 1961–)
*
Andrei Severny Solar Telescope
Andrei, Andrey or Andrej (in Cyrillic script: Андрэй , Андрей or Андреј) is a form of Andreas/Ἀνδρέας in Slavic languages and Romanian. People with the name include:
*Andrei of Polotsk (–1399), Lithuanian nobleman
*And ...
(90 cm diameter, 1954–) in
Crimea
Crimea, crh, Къырым, Qırım, grc, Κιμμερία / Ταυρική, translit=Kimmería / Taurikḗ ( ) is a peninsula in Ukraine, on the northern coast of the Black Sea, that has been occupied by Russia since 2014. It has a pop ...
*
Multi-purpose automated solar telescope (80 cm diameter) in Republic of Buryatia, Russia
*
Large solar vacuum telescope
Large means of great size.
Large may also refer to:
Mathematics
* Arbitrarily large, a phrase in mathematics
* Large cardinal, a property of certain transfinite numbers
* Large category, a category with a proper class of objects and morphisms (o ...
(76 cm diameter, 1980-) on the coast of lake Baikal, Russia
*
McMath-Hulbert Observatory (24"/61 cm diameter, 1941–1979)
*
Swedish Vacuum Solar Telescope The Swedish Vacuum Solar Telescope was a 47.5 cm solar telescope on La Palma in the Canary Islands. It was removed on 28 August 2000, and has been superseded by the Swedish 1-m Solar Telescope.
The Swedish Vacuum Solar Telescope awaits re-ass ...
(47.5 cm diameter, 1985–2000)
*
Swedish 1-m Solar Telescope (1 m diameter, 2002–)
*
Richard B. Dunn Solar Telescope (0.76 m diameter, 1969–)
*
Mount Wilson Observatory
The Mount Wilson Observatory (MWO) is an astronomical observatory in Los Angeles County, California, United States. The MWO is located on Mount Wilson, a peak in the San Gabriel Mountains near Pasadena, northeast of Los Angeles.
The observat ...
*
Dutch Open Telescope (45 cm diameter, 1997–)
* The
Teide Observatory
Teide Observatory ( es, Observatorio del Teide), IAU code 954, is an astronomical observatory on Mount Teide at , located on Tenerife, Spain. It has been operated by the Instituto de Astrofísica de Canarias since its inauguration in 1964. It bec ...
hosts multiple solar telescopes, including
** the 70 cm
Vacuum Tower Telescope
The Vacuum Tower Telescope is an evacuated-optics solar telescope located at the Teide Observatory on Tenerife in the Canary Islands. It is operated by the Kiepenheuer-Institut für Sonnenphysik (KIS).
It was built between 1983 and 1986, wi ...
(1989–) and
** the 1.5 m
GREGOR Solar Telescope
GREGOR is a solar telescope, equipped with a 1.5 m primary mirror, located at 2,390 m altitude at the Teide Observatory on Tenerife in the Canary Islands. It replaces the older Gregory Coudé Telescope and was inaugurated on May 21, 2012. First ...
(2012–]).
*
Goode Solar Telescope
The Goode Solar Telescope (GST) is a scientific facility for studies of the Sun named after Philip R. Goode.
It was the solar telescope with the world's largest aperture in operation for more than a decade. Located in Big Bear Lake; California ...
(1.6 m, 2009-)
* Chinese Large Solar Telescope (CLST) (180 cm diameter, 2019–)
*
Daniel K. Inouye Solar Telescope
The Daniel K. Inouye Solar Telescope (DKIST) is a scientific facility for studies of the sun at Haleakala Observatory on the Hawaiian island of Maui. Known as the Advanced Technology Solar Telescope (ATST) until 2013, it was named after Daniel K. ...
(DKIST), a telescope with 4m aperture.
*
European Solar Telescope
The European Solar Telescope (EST) is a pan-European project to build a next-generation 4-metre class solar telescope, to be located at the Roque de los Muchachos Observatory in the Canary Islands, Spain. It will use state-of-the-art instrument ...
(EST), a proposed 4-meter class aperture telescope.
*
Chinese Giant Solar Telescope
The Chinese Giant Solar Telescope (CGST) is a proposed solar telescope in China. CGST will be an infrared and optical solar telescope. Its spatial resolution is equivalent to an 8 m-diameter telescope, and the light-gathering power equivalent ...
(CGST), a proposed 5-8 meter aperture telescope.
*
National Large Solar Telescope (NLST), is a Gregorian multi-purpose open telescope proposed to be built and installed in India and aims to study the Sun's microscopic structure.
Other types of observation
Most solar observatories observe optically at visible, UV, and near infrared wavelengths, but other solar phenomena can be observed — albeit not from the Earth's surface due to the
absorption of the atmosphere:
* Solar X-ray astronomy, observations of the Sun in x-rays
* Multi-spectral solar telescope array (
MSSTA
The Multi-spectral solar telescope array, or MSSTA, was a sounding rocket payload built by Professor A.B.C. Walker, Jr. at Stanford University in the 1990s to test EUV/XUV imaging of the Sun using normal incidence EUV-reflective multilayer opti ...
), a rocket launched payload of UV telescopes in the 1990s
*
Leoncito Astronomical Complex
The El Leoncito Astronomical Complex (Spanish: Complejo Astronómico El Leoncito - CASLEO) is an astronomical observatory in the San Juan Province of Argentina. CASLEO is one of two observatories located within El Leoncito National Park, which i ...
operated a submillimeter wavelength solar telescope.
* The
Radio Solar Telescope Network {{unreferenced, date=August 2013
The Radio Solar Telescope Network (RSTN) is a network of solar observatories maintained and operated by the 557th Weather Wing, ACC. The RSTN consists of ground-based observatories in Australia, Italy, Massachusetts ...
(RSTN) is a network of solar observatories maintained and operated by the U.S.
Air Force Weather Agency.
*
CERN Axion Solar Telescope
The CERN Axion Solar Telescope (CAST) is an experiment in astroparticle physics to search for axions originating from the Sun. The experiment, sited at CERN in Switzerland, was commissioned in 1999 and came online in 2002 with the first da ...
(CAST), looks for solar
axions
An axion () is a hypothetical elementary particle postulated by the Peccei–Quinn theory in 1977 to resolve the strong CP problem in quantum chromodynamics (QCD). If axions exist and have low mass within a specific range, they are of interes ...
in the early 2000s
Amateur solar telescopes
In the field of
amateur astronomy
Amateur astronomy is a hobby where participants enjoy observing or imaging celestial objects in the sky using the unaided eye, binoculars, or telescopes. Even though scientific research may not be their primary goal, some amateur astronomers m ...
there are many methods used to observe the Sun. Amateurs use everything from simple systems to project the Sun on a piece of white paper, light blocking
filters
Filter, filtering or filters may refer to:
Science and technology
Computing
* Filter (higher-order function), in functional programming
* Filter (software), a computer program to process a data stream
* Filter (video), a software component tha ...
,
Herschel wedges which redirect 95% of the light and heat away from the eyepiece,
up to
hydrogen-alpha filter
H-alpha (Hα) is a specific deep-red visible spectral line in the Balmer series with a wavelength of 656.28 nm in air and 656.46 nm in vacuum; it occurs when a hydrogen electron falls from its third to second lowest energy level. H-alpha ...
systems and even home built
spectrohelioscope A spectrohelioscope is a type of solar telescope designed by George Ellery Hale in 1924 to allow the Sun to be viewed in a selected wavelength of light. The name comes from Latin- and Greek-based words: "Spectro," referring to the optical spectrum, ...
s. In contrast to professional telescopes, amateur solar telescopes are usually much smaller.
With a conventional telescope, an extremely dark filter at the opening of the primary tube is used to reduce the light of the sun to tolerable levels. Since the full available spectrum is observed, this is known as "white-light" viewing, and the opening filter is called a "white-light filter". The problem is that even reduced, the full spectrum of white light tends to obscure many of the specific features associated with solar activity, such as prominences and details of the
chromosphere
A chromosphere ("sphere of color") is the second layer of a star's atmosphere, located above the photosphere and below the solar transition region and corona. The term usually refers to the Sun's chromosphere, but not exclusively.
In the Su ...
(i.e., the surface). Specialized solar telescopes facilitate clear observation of such H-alpha emissions by using a bandwidth filter implemented with a
Fabry-Perot etalon.
[Morison, Ian (2016-12-25). H-alpha Solar Telescopes - An In-depth Discussion and Survey. Professor Morison's Astronomy Digest, 25 December 2016. Retrieved on 2020-04-17 from http://www.ianmorison.com/h-alpha-solar-telescopes-an-in-depth-discussion-and-survey/.]
See also
*
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 wavelengt ...
*
List of telescope types
The following are lists of devices categorized as types of telescopes or devices associated with telescopes. They are broken into major classifications with many variations due to professional, amateur, and commercial sub-types. Telescopes can be ...
*
Heliostat
A heliostat (from ''helios'', the Greek word for ''sun'', and ''stat'', as in stationary) is a device that includes a mirror, usually a plane mirror, which turns so as to keep reflecting sunlight toward a predetermined target, compensating ...
References
External links
* *
CSIRO Solar Heliographpart 2
Solar Gallery of an amateur astronomer
Solar Gallery of the Hong Kong Astronomical Society
*
{{Authority control
Astronomical instruments
Telescope
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 ...