# Radio astronomy

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Subfield of astronomy that studies celestial objects at radio frequencies

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The [Karl G. Jansky](/source/Karl_G._Jansky) [Very Large Array](/source/Very_Large_Array), a radio [interferometer](/source/Interferometry) in [New Mexico](/source/New_Mexico), United States

**Radio astronomy** is a subfield of [astronomy](/source/Astronomy) that studies [celestial objects](/source/Astronomical_object) using [radio waves](/source/Radio_wave). It started in 1933, when [Karl Jansky](/source/Karl_Jansky) at [Bell Telephone Laboratories](/source/Bell_Telephone_Laboratories) reported radiation coming from the [Milky Way](/source/Milky_Way). Subsequent observations have identified a number of different sources of radio emission. These include [stars](/source/Star) and [galaxies](/source/Galaxy), as well as entirely new classes of objects, such as [radio galaxies](/source/Radio_galaxy), [quasars](/source/Quasar), [pulsars](/source/Pulsar), and [masers](/source/Astrophysical_maser). The discovery of the [cosmic microwave background radiation](/source/Cosmic_microwave_background_radiation), regarded as evidence for the [Big Bang theory](/source/Big_Bang), was made through radio astronomy.

Radio astronomy is conducted using large [radio antennas](/source/Antenna_(radio)) referred to as *[radio telescopes](/source/Radio_telescope)*, that are either used alone, or with multiple linked telescopes utilizing the techniques of [radio interferometry](/source/Astronomical_interferometer) and [aperture synthesis](/source/Aperture_synthesis). The use of interferometry allows radio astronomy to achieve high [angular resolution](/source/Angular_resolution), as the resolving power of an interferometer is set by the distance between its components, rather than the size of its components.

Radio astronomy differs from *[radar astronomy](/source/Radar_astronomy)* in that the former is a passive observation (i.e., receiving only) and the latter an active one (transmitting and receiving).

## History

[Karl Jansky](/source/Karl_Jansky) and his rotating [directional antenna](/source/Directional_antenna) (early 1930s) in [Holmdel, New Jersey](/source/Holmdel%2C_New_Jersey), the world's first radio telescope, which was used to discover radio emissions from the [Milky Way](/source/Milky_Way)

Before [Karl Jansky](/source/Karl_Guthe_Jansky) observed the Milky Way in the 1930s, physicists speculated that radio waves could be observed from astronomical sources. In the 1860s, [James Clerk Maxwell](/source/James_Clerk_Maxwell)'s [equations](/source/Maxwell's_equations) had shown that [electromagnetic radiation](/source/Electromagnetic_radiation) is associated with [electricity](/source/Electricity) and [magnetism](/source/Magnetism), and could exist at any [wavelength](/source/Wavelength). Several attempts were made to detect radio emission from the [Sun](/source/Sun), including an experiment by German astrophysicists [Johannes Wilsing](/source/Johannes_Wilsing) and [Julius Scheiner](/source/Julius_Scheiner) in 1896 and a centimeter wave radiation apparatus set up by [Oliver Lodge](/source/Oliver_Lodge) between 1897 and 1900. These attempts were unable to detect any emission due to technical limitations of the instruments. The discovery of the radio-reflecting [ionosphere](/source/Ionosphere) in 1902 led physicists to conclude that the layer would bounce any astronomical radio transmission back into space, making them undetectable.[1]

[Karl Jansky](/source/Karl_Jansky) made the discovery of the first astronomical radio source [serendipitously](/source/Serendipity) in the early 1930s. As a newly hired radio engineer with [Bell Telephone Laboratories](/source/Bell_Labs), he was assigned the task to investigate static that might interfere with [short wave](/source/Short_wave) transatlantic voice transmissions. Using a large [directional antenna](/source/Directional_antenna), Jansky noticed that his [analog](/source/Analog_signal) pen-and-paper recording system kept recording a persistent repeating signal or "hiss" of unknown origin. Since the signal peaked about every 24 hours, Jansky first suspected the source of the interference was the [Sun](/source/Sun) crossing the view of his directional antenna. Continued analysis, however, showed that the source was not following the 24-hour daily cycle of the Sun exactly but instead repeating on a cycle of 23 hours and 56 minutes. Jansky discussed the puzzling phenomena with his friend, astrophysicist Albert Melvin Skellett, who pointed out that the observed time between the signal peaks was the exact length of a [sidereal day](/source/Sidereal_time): the time it took for "fixed" astronomical objects, such as a star, to pass in front of the antenna every time the Earth rotated.[2] By comparing his observations with optical astronomical maps, Jansky eventually concluded that the radiation source peaked when his antenna was aimed at the densest part of the [Milky Way](/source/Milky_Way) in the [constellation](/source/Constellation) of [Sagittarius](/source/Sagittarius_(constellation)).[3]

Jansky with a rough map of the night sky and pointing to the constellation of Cassiopeia. The wavy lines track the radio emissions he discovered on the chart paper, which also line up with the disk of the Milky Way.

Jansky announced his discovery at a meeting in Washington, D.C., in April 1933 and the field of radio astronomy was born.[4] In October 1933, his discovery was published in a journal article entitled "Electrical disturbances apparently of extraterrestrial origin" in the *[Proceedings of the Institute of Radio Engineers](/source/Proceedings_of_the_Institute_of_Radio_Engineers)*.[5] Jansky concluded that since the Sun (and therefore other stars) were not large emitters of radio noise, the strange radio interference may be generated by interstellar gas and dust in the galaxy, in particular, by "thermal agitation of charged particles."[2][6] (Jansky's peak radio source, one of the brightest in the sky, was designated [Sagittarius A](/source/Sagittarius_A) in the 1950s and was later hypothesized to be emitted by [electrons](/source/Electrons) in a strong magnetic field. Current thinking is that these are ions in orbit around a massive [black hole](/source/Black_hole) at the center of the galaxy at a point now designated as Sagittarius A*. The asterisk indicates that the particles at Sagittarius A are ionized.)[7][8][9][10]

After 1935, Jansky wanted to investigate the radio waves from the Milky Way in further detail, but Bell Labs reassigned him to another project, so he did no further work in the field of astronomy. His pioneering efforts in the field of radio astronomy have been recognized by the naming of the fundamental unit of [flux density](/source/Flux_density), the [jansky](/source/Jansky) (Jy), after him.[11]

[Grote Reber](/source/Grote_Reber)'s 9 meter antenna in his backyard in [Wheaton, Illinois](/source/Wheaton%2C_Illinois), the world's first parabolic radio telescope

[Radio amateur](/source/Radio_amateur) [Grote Reber](/source/Grote_Reber) was inspired by Jansky's work, and built a parabolic radio telescope 9 meters in diameter in his backyard in Wheaton, Illinois in 1937. He began by repeating Jansky's observations, and then conducted the first sky survey in the radio frequencies.[12] On February 27, 1942, [James Stanley Hey](/source/James_Stanley_Hey), a [British Army](/source/British_Army) research officer, made the first detection of radio waves emitted by the Sun.[13] Later that year, [George Clark Southworth](/source/George_Clark_Southworth),[14] at [Bell Labs](/source/Bell_Labs) like Jansky, also detected radiowaves from the Sun. Both researchers were bound by wartime security surrounding radar, so Reber, who was not, published his 1944 findings first.[15] Several other people independently discovered solar radio waves, including [E. Schott](https://en.wikipedia.org/w/index.php?title=E._Schott&action=edit&redlink=1) in [Denmark](/source/Denmark)[16] and [Elizabeth Alexander](/source/Elizabeth_Alexander_(scientist)) working on [Norfolk Island](/source/Norfolk_Island).[17][18][19][20]

Chart on which [Jocelyn Bell Burnell](/source/Jocelyn_Bell_Burnell) first recognised evidence of a [pulsar](/source/Pulsar), in 1967 (exhibited at [Cambridge University Library](/source/Cambridge_University_Library))

At [Cambridge University](/source/Cambridge_University), where ionospheric research had taken place during [World War II](/source/World_War_II), [J. A. Ratcliffe](/source/J._A._Ratcliffe) along with other members of the [Telecommunications Research Establishment](/source/Telecommunications_Research_Establishment) that had carried out wartime research into [radar](/source/Radar), created a radiophysics group at the university where radio wave emissions from the Sun were observed and studied. This early research soon branched out into the observation of other celestial radio sources and interferometry techniques were pioneered to isolate the angular source of the detected emissions. [Martin Ryle](/source/Martin_Ryle) and [Antony Hewish](/source/Antony_Hewish) at the [Cavendish Astrophysics Group](/source/Cavendish_Astrophysics_Group) developed the technique of Earth-rotation [aperture synthesis](/source/Aperture_synthesis). The radio astronomy group in Cambridge went on to found the [Mullard Radio Astronomy Observatory](/source/Mullard_Radio_Astronomy_Observatory) near Cambridge in the 1950s. During the late 1960s and early 1970s, as computers (such as the [Titan](/source/Titan_(1963_computer))) became capable of handling the computationally intensive [Fourier transform](/source/Fourier_transform) inversions required, they used aperture synthesis to create a 'One-Mile' and later a '5 km' effective aperture using the One-Mile and Ryle telescopes, respectively. They used the [Cambridge Interferometer](/source/Cambridge_Interferometer) to map the radio sky, producing the [Second](/source/Second_Cambridge_Catalogue_of_Radio_Sources) (2C) and [Third](/source/Third_Cambridge_Catalogue_of_Radio_Sources) (3C) Cambridge Catalogues of Radio Sources.[21]

## Techniques

Window of radio waves observable from Earth, on rough plot of Earth's atmospheric absorption and scattering (or [opacity](/source/Opacity_(optics))) of various [wavelengths](/source/Wavelength) of electromagnetic radiation

Radio astronomers use different techniques to observe objects in the radio spectrum. Instruments may simply be pointed at an energetic radio source to analyze its emission. To "image" a region of the sky in more detail, multiple overlapping scans can be recorded and pieced together in a [mosaic](/source/Mosaic) image. The type of instrument used depends on the strength of the signal and the amount of detail needed.

Observations from the [Earth](/source/Earth)'s surface are limited to wavelengths that can pass through the atmosphere. At low frequencies or long wavelengths, transmission is limited by the [ionosphere](/source/Ionosphere), which reflects waves with frequencies less than its characteristic [plasma frequency](/source/Plasma_frequency). Thus far, radio observations have been made at frequencies as low as 15 MHz.[22] [Water](/source/Water) [vapor](/source/Vapor) interferes with radio astronomy at higher frequencies, which has led to building radio observatories that conduct observations at [millimeter](/source/Millimeter) wavelengths at very high and dry sites to minimize the water vapor content in the line of sight. Finally, transmitting devices on Earth may cause [radio-frequency interference](/source/Radio-frequency_interference). Because of this, many radio observatories are built at remote places.

### Radio telescopes

Main article: [Radio telescope](/source/Radio_telescope)

Radio telescopes may need to be extremely large in order to receive signals with low [signal-to-noise ratio](/source/Signal-to-noise_ratio). Also since [angular resolution](/source/Angular_resolution) is a function of the diameter of the "[objective](/source/Objective_(optics))" in proportion to the wavelength of the electromagnetic radiation being observed, *[radio telescopes](/source/Radio_telescope)* have to be much larger in comparison to their [optical](/source/Optical_telescope) counterparts. For example, a 1-meter diameter optical telescope is two million times bigger than the wavelength of light observed giving it a resolution of roughly 0.3 [arc seconds](/source/Arc_second), whereas a radio telescope "dish" many times that size may, depending on the wavelength observed, only be able to resolve an object the size of the full moon (30 minutes of arc).

### Radio interferometry

Main article: [Astronomical interferometry](/source/Astronomical_interferometry)

See also: [Radio telescope § Radio interferometry](/source/Radio_telescope#Radio_interferometry)

The [Atacama Large Millimeter Array](/source/Atacama_Large_Millimeter_Array) (ALMA), many antennas linked together in a radio interferometer

 An optical image of the galaxy [M87](/source/Messier_87) ([HST](/source/Hubble_Space_Telescope)), a radio image of same galaxy using interferometry ([Very Large Array](/source/Very_Large_Array), VLA), and an image of the center section (VLBA) using a Very Long Baseline Array (Global VLBI) consisting of antennas in the US, Germany, Italy, Finland, Sweden and Spain. The jet of particles is suspected to be powered by a [black hole](/source/Black_hole) in the center of the galaxy.

The difficulty in achieving high resolutions with single radio telescopes led to radio [interferometry](/source/Interferometry), developed by British radio astronomer [Martin Ryle](/source/Martin_Ryle) and Australian engineer, radiophysicist, and radio astronomer [Joseph Lade Pawsey](/source/Joseph_Lade_Pawsey) and [Ruby Payne-Scott](/source/Ruby_Payne-Scott) in 1946. The first use of a radio interferometer for an astronomical observation was carried out by Payne-Scott, Pawsey and [Lindsay McCready](https://en.wikipedia.org/w/index.php?title=Lindsay_McCready&action=edit&redlink=1) on 26 January 1946 using a *single* converted radar antenna (broadside array) at [200 MHz](/source/Very_high_frequency) near [Sydney, Australia](/source/Sydney%2C_Australia). This group used the principle of a sea-cliff interferometer in which the antenna (formerly a World War II radar) observed the Sun at sunrise with interference arising from the direct radiation from the Sun and the reflected radiation from the sea. With this baseline of almost 200 meters, the authors determined that the solar radiation during the burst phase was much smaller than the solar disk and arose from a region associated with a large [sunspot](/source/Sunspot) group. The Australia group laid out the principles of [aperture synthesis](/source/Aperture_synthesis) in a groundbreaking paper published in 1947. The use of a sea-cliff [interferometer](/source/Interferometer) had been demonstrated by numerous groups in Australia, Iran and the UK during World War II, who had observed interference fringes (the direct radar return radiation and the reflected signal from the sea) from incoming aircraft.

The Cambridge group of Ryle and Vonberg observed the Sun at 175 MHz for the first time in mid-July 1946 with a Michelson interferometer consisting of two radio antennas with spacings of some tens of meters up to 240 meters. They showed that the radio radiation was smaller than 10 [arc minutes](/source/Minute_of_arc) in size and also detected circular polarization in the Type I bursts. Two other groups had also detected circular polarization at about the same time ([David Martyn](/source/David_Martyn_(scientist)) in Australia and [Edward Appleton](/source/Edward_Victor_Appleton) with [James Stanley Hey](/source/James_Stanley_Hey) in the UK).

Modern [radio interferometers](/source/Radio_telescope#radio_interferometry) consist of widely separated radio telescopes observing the same object that are connected together using [coaxial cable](/source/Coaxial_cable), [waveguide](/source/Waveguide), [optical fiber](/source/Optical_fiber), or other type of [transmission line](/source/Transmission_line). This not only increases the total signal collected, but it can also be used in a process called [aperture synthesis](/source/Aperture_synthesis) to vastly increase resolution. This technique works by superposing ("[interfering](/source/Interference_(wave_propagation))") the signal [waves](/source/Wave) from the different telescopes on the principle that [waves](/source/Wave) that coincide with the same [phase](/source/Phase_(waves)) will add to each other while two waves that have opposite phases will cancel each other out. This creates a combined telescope that is the size of the antennas furthest apart in the array. To produce a high-quality image, a large number of different separations between different telescopes are required (the projected separation between any two telescopes as seen from the radio source is called a "baseline") – as many different baselines as possible are required in order to get a good quality image. For example, the [Very Large Array](/source/Very_Large_Array) has 27 telescopes giving 351 independent baselines at once.

#### Very-long-baseline interferometry

Main article: [Very-long-baseline interferometry](/source/Very-long-baseline_interferometry)

Beginning in the 1970s, improvements in the stability of radio telescope receivers permitted telescopes from all over the world (and even in Earth orbit) to be combined to perform [very-long-baseline interferometry](/source/Very-long-baseline_interferometry). Instead of physically connecting the antennas, data received at each antenna is paired with timing information, usually from a local [atomic clock](/source/Atomic_clock), and then stored for later analysis on magnetic tape or hard disk. At that later time, the data is correlated with data from other antennas similarly recorded, to produce the resulting image. Using this method, it is possible to synthesise an antenna that is effectively the size of the Earth. The large distances between the telescopes enable very high angular resolutions to be achieved, much greater in fact than in any other field of astronomy. At the highest frequencies, synthesised beams less than 1 [milliarcsecond](/source/Minute_of_arc) are possible.

The pre-eminent VLBI arrays operating today are the [Very Long Baseline Array](/source/Very_Long_Baseline_Array) (with telescopes located across North America) and the [European VLBI Network](/source/European_VLBI_Network) (telescopes in Europe, China, South Africa and Puerto Rico). Each array usually operates separately, but occasional projects are observed together producing increased sensitivity. This is referred to as Global VLBI. There are also a VLBI networks, operating in Australia and New Zealand called the LBA (Long Baseline Array),[23] and arrays in Japan, China and South Korea which observe together to form the East-Asian VLBI Network (EAVN).[24]

Since its inception, recording data onto hard media was the only way to bring the data recorded at each telescope together for later correlation. However, the availability today of worldwide, high-bandwidth networks makes it possible to do VLBI in real time. This technique (referred to as e-VLBI) was originally pioneered in Japan, and more recently adopted in Australia and in Europe by the EVN (European VLBI Network) who perform an increasing number of scientific e-VLBI projects per year.[25]

## Astronomical sources

Main article: [Astronomical radio source](/source/Astronomical_radio_source)

See also: [Radio object with continuous optical spectrum](/source/Radio_object_with_continuous_optical_spectrum)

A radio image of the central region of the Milky Way galaxy. The arrow indicates a supernova remnant which is the location of a newly discovered transient, bursting low-frequency radio source [GCRT J1745-3009](/source/GCRT_J1745-3009).

Radio astronomy has led to substantial increases in astronomical knowledge, particularly with the discovery of several classes of new objects, including [pulsars](/source/Pulsar), [quasars](/source/Quasar)[26] and [radio galaxies](/source/Radio_galaxy). This is because radio astronomy allows us to see things that are not detectable in optical astronomy. Such objects represent some of the most extreme and energetic physical processes in the universe.

The [cosmic microwave background radiation](/source/Cosmic_microwave_background_radiation) was also first detected using radio telescopes. However, radio telescopes have also been used to investigate objects much closer to home, including observations of the [Sun](/source/Sun) and solar activity, and radar mapping of the [planets](/source/Solar_System).

Other sources include:

- [Sun](/source/Sun)

- [Jupiter](/source/Jupiter)

- [Sagittarius A](/source/Sagittarius_A), the [Galactic Center](/source/Galactic_Center) of the [Milky Way](/source/Milky_Way), with one portion [Sagittarius A*](/source/Sagittarius_A*) thought to be a radio wave–emitting [supermassive black hole](/source/Supermassive_black_hole)

- [Active galactic nuclei](/source/Active_galactic_nucleus) and [pulsars](/source/Pulsar) have jets of charged particles which emit [synchrotron radiation](/source/Synchrotron_radiation)

- Merging [galaxy clusters](/source/Galaxy_cluster) often show diffuse radio emission[27]

- [Supernova remnants](/source/Supernova_remnant) can also show diffuse radio emission; [pulsars](/source/Pulsar) are a type of supernova remnant that shows highly synchronous emission.

- The [cosmic microwave background](/source/Cosmic_microwave_background) is [blackbody](/source/Blackbody) radio/microwave emission

Earth's radio signal is mostly natural and stronger than for example Jupiter's but is produced by Earth's [auroras](/source/Aurora) and bounces at the [ionosphere](/source/Ionosphere) back into space.[28]

## International regulation

Antenna 70 m of the [Goldstone Deep Space Communications Complex](/source/Goldstone_Deep_Space_Communications_Complex), [California](/source/California)

Antenna 110m of the [Green Bank radio telescope](/source/Green_Bank_Telescope), US

Jupiter radio-bursts

**Radio astronomy service** (also: *radio astronomy radiocommunication service*) is, according to Article 1.58 of the [International Telecommunication Union's](/source/International_Telecommunication_Union) (ITU) [Radio Regulations](/source/ITU_Radio_Regulations) (RR),[29] defined as "A [radiocommunication service](/source/Radiocommunication_service) involving the use of radio astronomy". Subject of this radiocommunication service is to receive [radio waves](/source/Radio_wave) transmitted by [astronomical](/source/Astronomical_object) or celestial objects.

### Frequency allocation

The allocation of radio frequencies is provided according to *Article 5* of the ITU Radio Regulations (edition 2012).[30]

To improve harmonisation in spectrum utilisation, the majority of service-allocations stipulated in this document were incorporated in national Tables of Frequency Allocations and Utilisations which is within the responsibility of the appropriate national administration. The allocation might be primary, secondary, exclusive, and shared.

- primary allocation: indicated by writing in capital letters (see example below)

- secondary allocation: indicated by small letters

- exclusive or shared utilization: within the responsibility of administrations

In line to the appropriate [ITU Region](/source/International_Telecommunication_Union_region), the frequency bands are allocated (primary or secondary) to the *radio astronomy service* as follows.

Allocation to services Region 1 Region 2 Region 3 13 360–13 410 kHz FIXED RADIO ASTRONOMY 25 550–25 650 RADIO ASTRONOMY 37.5–38.25 MHz FIXED MOBILE Radio astronomy 322–328.6 FIXED MOBILE RADIO ASTRONOMY 406.1–410 FIXED MOBILE except aeronautical mobile RADIO ASTRONOMY 1 400–1 427 EARTH EXPLORATION-SATELLITE (passive) RADIO ASTRONOMY SPACE RESEARCH (passive) 1 610.6–1 613.8 MOBILE-SATELLITE (Earth-to-space) RADIO ASTRONOMY AERONAUTICAL RADIONAVIGATION 1 610.6–1 613.8 MOBILE-SATELLITE (Earth-to-space) RADIO ASTRONOMY AERONAUTICAL RADIONAVIGATION RADIODETERMINATION- SATELLITE (Earth-to-space) 1 610.6–1 613.8 MOBILE-SATELLITE (Earth-to-space) RADIO ASTRONOMY AERONAUTICAL RADIONAVIGATION Radiodetermination- satellite (Earth-to-space) 10.6–10.68 GHz RADIO ASTRONOMY and other services 10.68–10.7 RADIO ASTRONOMY and other services 14.47–14.5 RADIO ASTRONOMY and other services 15.35–15.4 RADIO ASTRONOMY and other services 22.21–22.5 RADIO ASTRONOMY and other services 23.6–24 RADIO ASTRONOMY and other services 31.3–31.5 RADIO ASTRONOMY and other services

## See also

- [Radio portal](https://en.wikipedia.org/wiki/Portal:Radio)
- [Astronomy portal](https://en.wikipedia.org/wiki/Portal:Astronomy)

- [Atacama Large Millimeter Array](/source/Atacama_Large_Millimeter_Array)

- [Submillimeter Array](/source/Submillimeter_Array)

- [Channel 37](/source/Channel_37)

- [Gamma-ray astronomy](/source/Gamma-ray_astronomy)

- [Infrared astronomy](/source/Infrared_astronomy)

- [Radar astronomy](/source/Radar_astronomy)

- [Time smearing](/source/Time_smearing)

- [X-ray astronomy](/source/X-ray_astronomy)

- [Waves (*Juno*)](/source/Waves_(Juno)) (radio instrument on the *Juno* Jupiter orbiter)

- [Radio Galaxy Zoo](/source/Radio_Galaxy_Zoo)

- [Würzburg radar#Post-war use in astronomy](/source/W%C3%BCrzburg_radar#Post-war_use_in_astronomy)

## References

1. **[^](#cite_ref-1)** F. Ghigo. ["Pre-History of Radio Astronomy"](http://www.nrao.edu/whatisra/hist_prehist.shtml). [National Radio Astronomy Observatory](/source/National_Radio_Astronomy_Observatory). [Archived](https://web.archive.org/web/20200615213814/http://www.nrao.edu/whatisra/hist_prehist.shtml) from the original on 2020-06-15. Retrieved 2010-04-09.

1. ^ [***a***](#cite_ref-bookrags.com_2-0) [***b***](#cite_ref-bookrags.com_2-1) [*World of Scientific Discovery on Karl Jansky*](http://www.bookrags.com/biography/karl-jansky-wsd/). [Archived](https://web.archive.org/web/20120121112928/http://www.bookrags.com/biography/karl-jansky-wsd/) from the original on 2012-01-21. Retrieved 2010-04-09.

1. **[^](#cite_ref-3)** Jansky, Karl G. (1933). ["Radio waves from outside the solar system"](https://doi.org/10.1038%2F132066a0). *Nature*. **132** (3323): 66. [Bibcode](/source/Bibcode_(identifier)):[1933Natur.132...66J](https://ui.adsabs.harvard.edu/abs/1933Natur.132...66J). [doi](/source/Doi_(identifier)):[10.1038/132066a0](https://doi.org/10.1038%2F132066a0). [S2CID](/source/S2CID_(identifier)) [4063838](https://api.semanticscholar.org/CorpusID:4063838).

1. **[^](#cite_ref-aas_4-0)** Hirshfeld, Alan (2018). ["Karl Jansky and the Discovery of Cosmic Radio Waves"](https://aas.org/posts/news/2018/07/month-astronomical-history-1). American Astronomical Society. [Archived](https://web.archive.org/web/20210929185905/https://aas.org/posts/news/2018/07/month-astronomical-history-1) from the original on 29 September 2021. Retrieved 21 September 2021. In April 1933, closing in on nearly two years of study, Jansky read his breakthrough paper, "Electrical Disturbances Apparently of Extraterrestrial Origin," before a meeting of the International Scientific Radio Union in Washington, DC. The strongest of the extraterrestrial waves, he found, emanate from a region in Sagittarius centered around right ascension 18 hours and declination — 20 degrees — in other words, from the direction of the galactic center. Jansky's discovery made the front page of the New York Times on 5 May 1933, and the field of radio astronomy was born.

1. **[^](#cite_ref-5)** [Jansky, Karl Guthe](/source/Karl_Guthe_Jansky) (October 1933). "Electrical disturbances apparently of extraterrestrial origin". *Proc. IRE*. **21** (10): 1387. [Bibcode](/source/Bibcode_(identifier)):[1933PIRE...21.1387J](https://ui.adsabs.harvard.edu/abs/1933PIRE...21.1387J). [doi](/source/Doi_(identifier)):[10.1109/JRPROC.1933.227458](https://doi.org/10.1109%2FJRPROC.1933.227458). Reprinted 65 years later as [Jansky, Karl Guthe](/source/Karl_Guthe_Jansky) (July 1998). "Electrical disturbances apparently of extraterrestrial origin". *[Proc. IEEE](/source/Proc._IEEE)*. **86** (7): 1510–1515. [Bibcode](/source/Bibcode_(identifier)):[1998IEEEP..86.1510J](https://ui.adsabs.harvard.edu/abs/1998IEEEP..86.1510J). [doi](/source/Doi_(identifier)):[10.1109/JPROC.1998.681378](https://doi.org/10.1109%2FJPROC.1998.681378). [S2CID](/source/S2CID_(identifier)) [47549559](https://api.semanticscholar.org/CorpusID:47549559). along with an explanatory preface in Imbriale, W.A. (1998). "Introduction to "Electrical Disturbances Apparently of Extraterrestrial Origin"". *Proc. IEEE*. **86** (7): 1507–1509. [Bibcode](/source/Bibcode_(identifier)):[1998IEEEP..86.1507I](https://ui.adsabs.harvard.edu/abs/1998IEEEP..86.1507I). [doi](/source/Doi_(identifier)):[10.1109/JPROC.1998.681377](https://doi.org/10.1109%2FJPROC.1998.681377)..

1. **[^](#cite_ref-6)** [Jansky, Karl Guthe](/source/Karl_Guthe_Jansky) (October 1935). "A note on the source of interstellar interference". *Proc. IRE*. **23** (10): 1158. [Bibcode](/source/Bibcode_(identifier)):[1935PIRE...23.1158J](https://ui.adsabs.harvard.edu/abs/1935PIRE...23.1158J). [doi](/source/Doi_(identifier)):[10.1109/JRPROC.1935.227275](https://doi.org/10.1109%2FJRPROC.1935.227275). [S2CID](/source/S2CID_(identifier)) [51632813](https://api.semanticscholar.org/CorpusID:51632813).

1. **[^](#cite_ref-7)** Belusević, R. (2008). [*Relativity, Astrophysics and Cosmology: Volume 1*](https://books.google.com/books?id=WeICTHIxP2MC&pg=PA163). Wiley-VCH. p. 163. [ISBN](/source/ISBN_(identifier)) [978-3-527-40764-4](https://en.wikipedia.org/wiki/Special:BookSources/978-3-527-40764-4).

1. **[^](#cite_ref-8)** Kambič, B. (6 October 2009). [*Viewing the Constellations with Binoculars*](https://books.google.com/books?id=3vxLNPNHOcwC&pg=PA131). [Springer](/source/Springer_(publisher)). pp. 131–133. [ISBN](/source/ISBN_(identifier)) [978-0-387-85355-0](https://en.wikipedia.org/wiki/Special:BookSources/978-0-387-85355-0).

1. **[^](#cite_ref-9)** Gillessen, S.; Eisenhauer, F.; Trippe, S.; et al. (2009). "Monitoring Stellar Orbits around the Massive Black Hole in the Galactic Center". *The Astrophysical Journal*. **692** (2): 1075–1109. [arXiv](/source/ArXiv_(identifier)):[0810.4674](https://arxiv.org/abs/0810.4674). [Bibcode](/source/Bibcode_(identifier)):[2009ApJ...692.1075G](https://ui.adsabs.harvard.edu/abs/2009ApJ...692.1075G). [doi](/source/Doi_(identifier)):[10.1088/0004-637X/692/2/1075](https://doi.org/10.1088%2F0004-637X%2F692%2F2%2F1075). [S2CID](/source/S2CID_(identifier)) [1431308](https://api.semanticscholar.org/CorpusID:1431308).

1. **[^](#cite_ref-10)** Brown, R.L. (1982). ["Precessing jets in Sagittarius A – Gas dynamics in the central parsec of the galaxy"](https://doi.org/10.1086%2F160401). *Astrophysical Journal*. **262**: 110–119. [Bibcode](/source/Bibcode_(identifier)):[1982ApJ...262..110B](https://ui.adsabs.harvard.edu/abs/1982ApJ...262..110B). [doi](/source/Doi_(identifier)):[10.1086/160401](https://doi.org/10.1086%2F160401).

1. **[^](#cite_ref-aps_11-0)** ["This Month in Physics History May 5, 1933: The New York Times Covers Discovery of Cosmic Radio Waves"](https://www.aps.org/publications/apsnews/201505/physicshistory.cfm). *aps.org*. American Physical Society (May 2015) Volume 24, Number 5. [Archived](https://web.archive.org/web/20210914000424/https://www.aps.org/publications/apsnews/201505/physicshistory.cfm) from the original on 14 September 2021. Retrieved 21 September 2021. Jansky died in 1950 at the age of 44, the result of a massive stroke stemming from his kidney disease. When that first 1933 paper was reprinted in Proceedings of the IEEE in 1984, the editors noted that Jansky's work would mostly likely have won a Nobel prize, had the scientist not died so young. Today the "jansky" is the unit of measurement for radio wave intensity (flux density).

1. **[^](#cite_ref-12)** ["Grote Reber"](http://www.nrao.edu/whatisra/hist_reber.shtml). [Archived](https://web.archive.org/web/20200807095454/https://www.nrao.edu/whatisra/hist_reber.shtml) from the original on 2020-08-07. Retrieved 2010-04-09.

1. **[^](#cite_ref-13)** Hey, J.S. (1975). *Radio Universe* (2nd ed.). [Pergamon Press](/source/Pergamon_Press). [ISBN](/source/ISBN_(identifier)) [978-0080187617](https://en.wikipedia.org/wiki/Special:BookSources/978-0080187617).

1. **[^](#cite_ref-14)** Southworth, G.C. (1945). "Microwave radiation from the Sun". *Journal of the Franklin Institute*. **239** (4): 285–297. [Bibcode](/source/Bibcode_(identifier)):[1945FrInJ.239..285S](https://ui.adsabs.harvard.edu/abs/1945FrInJ.239..285S). [doi](/source/Doi_(identifier)):[10.1016/0016-0032(45)90163-3](https://doi.org/10.1016%2F0016-0032%2845%2990163-3).

1. **[^](#cite_ref-15)** Kellerman, K. I. (1999). "Grote Reber's Observations on Cosmic Static". *Astrophysical Journal*. **525C**: 371. [Bibcode](/source/Bibcode_(identifier)):[1999ApJ...525C.371K](https://ui.adsabs.harvard.edu/abs/1999ApJ...525C.371K).

1. **[^](#cite_ref-16)** Schott, E. (1947). ["175 MHz-Strahlung der Sonne"](https://doi.org/10.1002%2Fphbl.19470030508). *Physikalische Blätter* (in German). **3** (5): 159–160. [doi](/source/Doi_(identifier)):[10.1002/phbl.19470030508](https://doi.org/10.1002%2Fphbl.19470030508).

1. **[^](#cite_ref-17)** Alexander, F.E.S. (1945). *Long Wave Solar Radiation*. [Department of Scientific and Industrial Research](/source/Department_of_Scientific_and_Industrial_Research_(New_Zealand)), Radio Development Laboratory.

1. **[^](#cite_ref-18)** Alexander, F.E.S. (1945). *Report of the Investigation of the "Norfolk Island Effect"*. [Department of Scientific and Industrial Research](/source/Department_of_Scientific_and_Industrial_Research_(New_Zealand)), Radio Development Laboratory. [Bibcode](/source/Bibcode_(identifier)):[1945rdlr.book.....A](https://ui.adsabs.harvard.edu/abs/1945rdlr.book.....A).

1. **[^](#cite_ref-19)** Alexander, F.E.S. (1946). "The Sun's radio energy". *Radio & Electronics*. **1** (1): 16–17. (see [*R&E* holdings at NLNZ](http://nlnzcat.natlib.govt.nz/vwebv/holdingsInfo?bibId=405978) [Deprecated link](https://en.wikipedia.org/wiki/Wikipedia:Archive.today_guidance) archived 2016-07-23 at [archive.today](/source/Archive.today).)

1. **[^](#cite_ref-Orchiston_20-0)** Orchiston, W. (2005). "Dr Elizabeth Alexander: First Female Radio Astronomer". *The New Astronomy: Opening the Electromagnetic Window and Expanding Our View of Planet Earth*. Astrophysics and Space Science Library. Vol. 334. pp. 71–92. [doi](/source/Doi_(identifier)):[10.1007/1-4020-3724-4_5](https://doi.org/10.1007%2F1-4020-3724-4_5). [ISBN](/source/ISBN_(identifier)) [978-1-4020-3723-8](https://en.wikipedia.org/wiki/Special:BookSources/978-1-4020-3723-8).

1. **[^](#cite_ref-21)** ["Radio Astronomy"](https://web.archive.org/web/20131110022209/http://www.phy.cam.ac.uk/history/years/radioast.php). Cambridge University: Department of Physics. Archived from [the original](http://www.phy.cam.ac.uk/history/years/radioast.php) on 2013-11-10.

1. **[^](#cite_ref-22)** Groeneveld, C.; van Weeren, R. J.; Osinga, E.; Williams, W. L.; Callingham, J. R.; de Gasperin, F.; Botteon, A.; Shimwell, T.; Sweijen, F.; de Jong, J. M. G. H. J.; Jansen, L. F.; Miley, G. K.; Brunetti, G.; Brüggen, M.; Röttgering, H. J. A. (6 May 2024). "Characterization of the decametre sky at subarcminute resolution". *Nature Astronomy*. **8** (6): 786–795. [arXiv](/source/ArXiv_(identifier)):[2405.05311](https://arxiv.org/abs/2405.05311). [Bibcode](/source/Bibcode_(identifier)):[2024NatAs...8..786G](https://ui.adsabs.harvard.edu/abs/2024NatAs...8..786G). [doi](/source/Doi_(identifier)):[10.1038/s41550-024-02266-z](https://doi.org/10.1038%2Fs41550-024-02266-z).

1. **[^](#cite_ref-23)** ["VLBI at the ATNF"](http://www.atnf.csiro.au/vlbi/). 7 December 2016. [Archived](https://web.archive.org/web/20210501051105/https://www.atnf.csiro.au/vlbi/) from the original on 1 May 2021. Retrieved 16 June 2015.

1. **[^](#cite_ref-24)** ["East Asia VLBI Network and Asia Pacific Telescope"](http://www.astro.sci.yamaguchi-u.ac.jp/eavn/index.html). [Archived](https://web.archive.org/web/20210428080543/http://astro.sci.yamaguchi-u.ac.jp/eavn/index.html) from the original on 2021-04-28. Retrieved 2015-06-16.

1. **[^](#cite_ref-25)** ["A technological breakthrough for radio astronomy – Astronomical observations via high-speed data link"](http://www.innovations-report.com/html/reports/physics_astronomy/report-25117.html). 26 January 2004. [Archived](https://web.archive.org/web/20081203145055/http://www.innovations-report.com/html/reports/physics_astronomy/report-25117.html) from the original on 2008-12-03. Retrieved 2008-07-22.

1. **[^](#cite_ref-Shields_26-0)** Shields, Gregory A. (1999). ["A brief history of AGN"](http://ned.ipac.caltech.edu/level5/Sept04/Shields/Shields3.html). *The Publications of the Astronomical Society of the Pacific*. **111** (760): 661–678. [arXiv](/source/ArXiv_(identifier)):[astro-ph/9903401](https://arxiv.org/abs/astro-ph/9903401). [Bibcode](/source/Bibcode_(identifier)):[1999PASP..111..661S](https://ui.adsabs.harvard.edu/abs/1999PASP..111..661S). [doi](/source/Doi_(identifier)):[10.1086/316378](https://doi.org/10.1086%2F316378). [S2CID](/source/S2CID_(identifier)) [18953602](https://api.semanticscholar.org/CorpusID:18953602). [Archived](https://web.archive.org/web/20090912025415/http://nedwww.ipac.caltech.edu/level5/Sept04/Shields/Shields3.html) from the original on 12 September 2009. Retrieved 3 October 2014.

1. **[^](#cite_ref-27)** ["Conclusion"](https://web.archive.org/web/20060128231925/http://www.arcetri.astro.it/~buttery/thesis/node69.html). Archived from [the original](http://www.arcetri.astro.it/~buttery/thesis/node69.html) on 2006-01-28. Retrieved 2006-03-29.

1. **[^](#cite_ref-Geophysical_Institute_1983_r818_28-0)** ["The Earth is a Strong Radio Source even without Man's Tinkering"](https://www.gi.alaska.edu/alaska-science-forum/earth-strong-radio-source-even-without-mans-tinkering). *Geophysical Institute*. June 23, 1983. Retrieved May 2, 2024.

1. **[^](#cite_ref-29)** ITU Radio Regulations, Section IV. Radio Stations and Systems – Article 1.58, definition: *radio astronomy service / radio astronomy radiocommunication service*

1. **[^](#cite_ref-30)** *ITU Radio Regulations, CHAPTER II – Frequencies, ARTICLE 5 Frequency allocations, Section IV – Table of Frequency Allocations*

## Further reading

**Journals**

- Gart Westerhout (1972). "The early history of radio astronomy". *[Annals of the New York Academy of Sciences](/source/Annals_of_the_New_York_Academy_of_Sciences)*. **189** (1): 211–218. [Bibcode](/source/Bibcode_(identifier)):[1972NYASA.198..211W](https://ui.adsabs.harvard.edu/abs/1972NYASA.198..211W). [doi](/source/Doi_(identifier)):[10.1111/j.1749-6632.1972.tb12724.x](https://doi.org/10.1111%2Fj.1749-6632.1972.tb12724.x). [S2CID](/source/S2CID_(identifier)) [56034495](https://api.semanticscholar.org/CorpusID:56034495).

- Hendrik Christoffel van de Hulst (1945). "Radiostraling uit het wereldruim. II. Herkomst der radiogolven". *Nederlands Tijdschrift voor Natuurkunde* (in Dutch). **11**: 210–221.

**Books**

- [Gerrit Verschuur](/source/Gerrit_Verschuur) *The Invisible Universe: The Story of Radio Astronomy* Springer 2015

- Bruno Bertotti (ed.), *Modern Cosmology in Retrospect*. Cambridge University Press 1990.

- James J. Condon, et al.: *Essential Radio Astronomy.* Princeton University Press, Princeton 2016, [ISBN](/source/ISBN_(identifier)) [9780691137797](https://en.wikipedia.org/wiki/Special:BookSources/9780691137797).

- Robin Michael Green, *Spherical Astronomy*. Cambridge University Press, 1985.

- Raymond Haynes, Roslynn Haynes, and Richard McGee, *Explorers of the Southern Sky: A History of Australian Astronomy*. Cambridge University Press 1996.

- J.S. Hey, *The Evolution of Radio Astronomy.* Neale Watson Academic, 1973.

- David L. Jauncey, *Radio Astronomy and Cosmology.* Springer 1977.

- [Roger Clifton Jennison](/source/Roger_Clifton_Jennison), *Introduction to Radio Astronomy*. 1967.

- Jobn D. Kraus, Martt; E. Tiuri, and Antti V. Räisänen, *Radio Astronomy*, 2nd ed, Cygnus-Quasar Books, 1986.

- Albrecht Krüger, *Introduction to Solar Radio Astronomy and Radio Physics.* Springer 1979.

- David P.D. Munns, *A Single Sky: How an International Community Forged the Science of Radio Astronomy.* Cambridge, MA: MIT Press, 2013.

- Allan A. Needell, *Science, Cold War and American State: Lloyd V. Berkner and the Balance of Professional Ideals*. Routledge, 2000.

- Joseph Lade Pawsey and Ronald Newbold Bracewell, *Radio Astronomy.* Clarendon Press, 1955.

- Kristen Rohlfs, Thomas L Wilson, *Tools of Radio Astronomy*. Springer 2003.

- D.T. Wilkinson and P.J.E. Peebles, *Serendipitous Discoveries in Radio Astronomy.* Green Bank, WV: National Radio Astronomy Observatory, 1983.

- Woodruff T. Sullivan III, *The Early Years of Radio Astronomy: Reflections Fifty Years after Jansky's Discovery.* Cambridge, England: Cambridge University Press, 1984.

- Woodruff T. Sullivan III, *Cosmic Noise: A History of Early Radio Astronomy.* Cambridge University Press, 2009.

- Woodruff T. Sullivan III, *Classics in Radio Astronomy*. Reidel Publishing Company, Dordrecht, 1982.

## External links

Wikimedia Commons has media related to [Radio astronomy](https://commons.wikimedia.org/wiki/Category:Radio_astronomy).

- [nrao.edu National Radio Astronomy Observatory](https://public.nrao.edu/)

- [The History of Radio Astronomy](https://archive.today/19990202131951/http://web.haystack.mit.edu/education/radiohist.html) * [Reber Radio Telescope – National Park Services](https://web.archive.org/web/20020328074733/http://www.cr.nps.gov/history/online_books/butowsky5/astro4o.htm)

- [Radio Telescope Developed](https://web.archive.org/web/20040307044635/http://edmall.gsfc.nasa.gov/aacps/news/Radio_Telescope.html) – a brief history from [NASA](/source/NASA) [Goddard Space Flight Center](/source/Goddard_Space_Flight_Center)

- [Society of Amateur Radio Astronomers](https://www.radio-astronomy.org/)

- [Visualization of Radio Telescope Data Using Google Earth](http://www.ogleearth.com/2007/09/xml_or_the_comi.html)

- [UnwantedEmissions.com A general reference for radio spectrum allocations, including radio astronomy.](http://www.unwantedemissions.com)

- [Improving Radio Astronomy Images by Array Processing](http://www.levanda.co.il/ronny/RadioAstronomy_SignalProcessing.html) [Archived](https://web.archive.org/web/20110404054247/http://www.levanda.co.il/ronny/RadioAstronomy_SignalProcessing.html) 2011-04-04 at the [Wayback Machine](/source/Wayback_Machine)

- [What is Radio Astronomy](https://archive.today/20130704122042/http://www.radioastrolab.it/en/radio-astronomy/what-is-radio-astronomy/) – Radioastrolab

- [PICTOR: A free-to-use radio telescope](https://www.pictortelescope.com/)

v t e Electromagnetic spectrum Gamma rays X-rays Ultraviolet Visible Infrared Microwave Radio ← higher frequencies, higher energy, shorter wavelengths longer wavelengths, lower frequencies, lower energy → Gamma rays Very-high-energy Ultra-high-energy X-rays Soft X-ray Hard X-ray High-energy X-rays Ultraviolet Extreme ultraviolet Vacuum ultraviolet Lyman-alpha FUV MUV NUV UVC UVB UVA Visible (optical) Violet Blue Cyan Green Yellow Orange Red Infrared NIR (Bands: J, K, H) SWIR MWIR (Bands: L, M, N) LWIR FIR Microwaves W band V band Q band Ka band K band Ku band X band C band S band L band Radio THF EHF SHF UHF VHF HF MF LF VLF ULF SLF ELF Wavelength types Microwave Shortwave Medium wave Longwave

v t e Radio astronomy Concepts Units (watt and jansky) Radio telescope (Radio window) Astronomical interferometer (History) Very Long Baseline Interferometry (VLBI) Astronomical radio source Radio telescopes (List) Individual telescopes 500 meter Aperture Spherical Telescope (FAST, China) Arecibo Telescope (Puerto Rico, US) Caltech Submillimeter Observatory (CSO, US) Effelsberg Telescope (Germany) Galenki RT-70 (Russia) Green Bank Telescope (West Virginia, US) Greenland Telescope (Greenland, Denmark) Large Millimeter Telescope (Mexico) Lovell Telescope (UK) Ooty Telescope (India) Qitai Radio Telescope (China) RATAN-600 Radio Telescope (Russia) Sardinia Radio Telescope (Italy) Suffa RT-70 (Uzbekistan) Usuda Telescope (Japan) UTR-2 decameter radio telescope (Ukraine) Yevpatoria RT-70 (Ukraine) Southern Hemisphere HartRAO (South Africa) Parkes Observatory (Australia) Warkworth Radio Astronomical Observatory (NZ) Interferometers Allen Telescope Array (ATA, California, US) Atacama Large Millimeter Array (ALMA, Chile) Australia Telescope Compact Array (ATCA, Australia) Australian Square Kilometre Array Pathfinder (ASKAP, Australia) Canadian Hydrogen Intensity Mapping Experiment (CHIME, Canada) Combined Array for Research in Millimeter-wave Astronomy (CARMA, California, US) European VLBI Network (Europe) Event Horizon Telescope (EHT) Giant Metrewave Radio Telescope (GMRT, India) Green Bank Interferometer (GBI, West Virginia, US) Korean VLBI Network (KVN, South Korea) Large Latin American Millimeter Array (LLAMA, Argentina/Brazil) Long Wavelength Array (LWA, New Mexico, US) Low-Frequency Array (LOFAR, Netherlands) MeerKAT (South Africa) Molonglo Observatory Synthesis Telescope (MOST, Australia) Multi-Element Radio Linked Interferometer Network (MERLIN, UK) Murchison Widefield Array (MWA, Australia) Northern Cross Radio Telescope (Italy) Northern Extended Millimeter Array (France) One-Mile Telescope (UK) Primeval Structure Telescope (PaST, China) Square Kilometre Array (SKA, Australia, South Africa) Submillimeter Array (SMA, US) Very Large Array (VLA, New Mexico, US) Very Long Baseline Array (VLBA, US) Westerbork Synthesis Radio Telescope (WSRT, Netherlands) Space-based HALCA (Japan) Spektr-R (Russia) Observatories Algonquin Radio Observatory (Canada) Arecibo Observatory (Puerto Rico, US) Green Bank Observatory (US) Haystack Observatory (US) Jodrell Bank Observatory (UK) Mullard Radio Astronomy Observatory (UK) National Radio Astronomy Observatory (US) Nançay Radio Observatory (France) Onsala Space Observatory (Sweden) Pushchino Radio Astronomy Observatory (PRAO ASC LPI, Russia) Special Astrophysical Observatory of the Russian Academy of Science (SAORAS, Russia) Vermilion River Observatory (US) Multi-use DRAO (Canada) ESA New Norcia (Australia) PARL (Canada) People Elizabeth Alexander John G. Bolton Edward George Bowen Ronald Bracewell Jocelyn Bell Burnell Arthur Covington Nan Dieter-Conklin Frank Drake Cyril Hazard Antony Hewish Sebastian von Hoerner Karl Guthe Jansky Kenneth Kellermann Frank J. Kerr John D. Kraus Bernard Lovell Christiaan Alexander Muller Jan Oort Joseph Lade Pawsey Ruby Payne-Scott Arno Penzias Grote Reber Martin Ryle Govind Swarup Gart Westerhout Paul Wild Robert Wilson Astronomy by EM methods Submillimetre astronomy Infrared astronomy Optical astronomy High-energy astronomy Gravitational-wave astronomy Related articles Aperture synthesis Cosmic microwave background radiation Interferometry Odd radio circle Pulsar timing array Radio propagation SETI Wow! signal HD 164595 signal Solar radio emission Category Commons

v t e Astronomy Outline History Timeline Astronomer Astronomical symbols Astronomical object Glossary ... in space Astronomy by Manner Amateur Observational Sidewalk Space telescope Celestial subject Galactic / Extragalactic Local system Solar EM methods Radio Submillimetre Infrared (Far-infrared) Visible-light (optical) Ultraviolet X-ray History Gamma-ray Other methods Neutrino Cosmic rays Gravitational radiation High-energy Radar Spherical Multi-messenger Culture Australian Aboriginal Babylonian Chinese Egyptian Greek Hebrew Indian Inuit Maya Medieval Islamic Persian Serbian folk Tibetan Optical telescopes List Category Extremely large telescope Astrograph Extremely Large Telescope Gran Telescopio Canarias Hale Telescope Hubble Space Telescope Keck Observatory Large Binocular Telescope Southern African Large Telescope Very Large Telescope Related Archaeoastronomy Astrobiology Astrochemistry Astroinformatics Astrology and astronomy Astrometry Astronomers Monument Astroparticle physics Astrophysics Astrotourism Binoculars Constellation IAU Cosmogony Photometry Planetarium Planetary geology Physical cosmology Quantum cosmology List of astronomers French Medieval Islamic Russian Women Telescope X-ray telescope history lists Zodiac List of astronomical catalogues Category Commons

Authority control databases International GND FAST National United States France BnF data Japan Czech Republic Spain Israel Other Yale LUX

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Adapted from the Wikipedia article [Radio astronomy](https://en.wikipedia.org/wiki/Radio_astronomy) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Radio_astronomy?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.