VLA Telescope: What It Is, What It Does, and Latest Discoveries
Telescope Advisor Logo Telescope Advisor
The Milky Way galaxy structure — the VLA telescope has mapped vast regions of our galaxy at radio wavelengths invisible to optical telescopes, revealing jets, supernova remnants and star-forming regions

Telescope Guide · Radio Astronomy

The VLA Telescope: What It Is, How It Works, and What It's Discovered

The Karl G. Jansky Very Large Array — the VLA — is the world's most productive radio telescope facility: 27 dish antennas spread across 36 kilometres of New Mexico desert, acting as a single instrument of extraordinary power. It sees a universe completely invisible to optical telescopes: jets from black holes, star-forming gas clouds, megamasers in distant galaxies, and the radio emission of exoplanets. Here's everything you need to know.

LocationPlains of San Agustin, New Mexico
Dishes27 antennas, each 25m diameter
Maximum baseline36 km — equivalent resolution to a giant telescope
Operational since1980 — upgraded to JVLA in 2012
By Telescope Advisor Editorial Team Published: Updated: Editorial Standards

Quick Overview: The VLA at a Glance

The Karl G. Jansky Very Large Array (commonly called the VLA) is a radio astronomy observatory operated by the National Radio Astronomy Observatory (NRAO) on behalf of the National Science Foundation (NSF). Located on the high desert plain (altitude: 2,124m) 50 miles west of Socorro, New Mexico, it is one of the most recognisable scientific installations on Earth — its 27 white dish antennas arranged in a Y-pattern are a familiar sight in scientific photography and have appeared in films (Contact, 1997) and documentaries for decades.

The observatory

  • Full name: Karl G. Jansky Very Large Array
  • Operator: NRAO / National Science Foundation
  • Location: Socorro County, New Mexico (34.08°N, 107.62°W)
  • Altitude: 2,124 metres (6,969 ft)
  • Opened: 1980
  • Major upgrade: 2012 (JVLA — expanded frequency range)
  • Annual proposals received: ~900 (from global astronomers)

Technical specs

  • Number of dishes: 27 active + 1 spare
  • Dish diameter: 25 metres each
  • Total collecting area: ~13,000 m² (equivalent 130m single dish)
  • Baseline (max): 36.4 km (A configuration)
  • Frequency range: 1–50 GHz (after JVLA upgrade)
  • Array configurations: A, B, C, D (4 sizes)
  • Dish movement: Each dish moves on rails on the Y-arms

Science output

  • Papers published: 500+ per year
  • Observations since 1980: Hundreds of thousands
  • Nobel Prize connections: Multiple (Taylor & Hulse 1993)
  • Sky surveys completed: FIRST, NVSS, VLASS and others
  • Open access: Proposals accepted from any scientist worldwide
  • Visitor centre: Open to public, free admission


How Radio Telescopes Work

Radio telescopes detect electromagnetic radiation in the radio frequency range — wavelengths from roughly 1 millimetre to 10 metres. This is the same type of electromagnetic radiation as visible light, X-rays, and gamma rays — it differs only in wavelength. Radio waves are much longer than visible light (550 nanometres) — centimetres to metres compared to billionths of a metre — and they interact with matter very differently.

What produces radio waves in space?

  • Synchrotron radiation: Electrons moving at near-light-speed in magnetic fields produce intense radio emission — this is the signature of relativistic jets from black holes and pulsar wind nebulae.
  • Hydrogen (21cm line): Neutral hydrogen atoms throughout the Universe emit radio waves at exactly 21.1cm wavelength. This lets radio telescopes map the distribution of hydrogen gas across entire galaxies — tracing the "skeleton" of the cosmic web.
  • Masers: Cosmic microwave amplification (like a natural laser but for radio waves) occurs in star-forming regions and the envelopes of evolved stars. Megamasers in distant galaxies are among the most luminous radio sources known.
  • Pulsars: Rotating neutron stars emit radio beams like a cosmic lighthouse, with periods measured to extraordinary precision.
  • Thermal emission: Warm gas and dust emit radio waves according to their temperature — planets, protoplanetary disks, and molecular clouds all have characteristic radio signatures.

Why radio telescopes need to be so large

The same physics that governs optical telescopes — the Rayleigh criterion — applies to radio telescopes. Resolution scales with wavelength divided by aperture. Radio waves are millions of times longer than visible light. To achieve the same resolution as a modest optical telescope, a radio telescope would need to be millions of metres in diameter. The solution: interferometry. By combining signals from multiple widely-separated dishes simultaneously, the VLA simulates the resolution of a telescope equal in size to the maximum separation between its dishes — up to 36 kilometres. This technique is called aperture synthesis or interferometry, and it's what makes the VLA's power possible despite individual dish sizes of "only" 25 metres.

The resolution comparison

At 6cm wavelength (5 GHz) in A-configuration (36km baseline), the VLA achieves about 0.3 arcseconds resolution — comparable to a 6-inch optical telescope. But it's observing phenomena completely invisible to any optical telescope: jets of plasma, radio-bright star-forming regions, and the magnetospheres of exoplanets.

How the VLA Achieves Its Extraordinary Power

The VLA operates as an aperture synthesis interferometer. Each of its 27 antennas receives radio signals from the sky simultaneously. These signals are then combined electronically at a central correlation facility, where the slight time difference in arrival between each pair of dishes encodes both the intensity and direction of the radio source. By computing the cross-correlations between all 351 unique antenna pairs, the array reconstructs a detailed image of the radio sky with resolution set by the maximum baseline (separation between the farthest dishes), not the size of any individual dish.

Milky Way galaxy — the VLA has mapped extensive radio-emitting regions of our galaxy including the galactic centre, supernova remnants, and hydrogen gas distribution

The Milky Way — extensively mapped by the VLA at radio wavelengths

The VLA's surveys of the galactic centre region revealed supernova remnants, molecular clouds, and the radio continuum emission of our galaxy with unprecedented clarity. Credit: NASA.

The correlator: the VLA's digital brain

The 2012 JVLA upgrade replaced the VLA's original analogue correlator with the WIDAR (Wideband Interferometric Digital ARchitecture) correlator — a supercomputer that processes 8 gigabits per second of data from all 27 antennas simultaneously and can observe up to 8 GHz of bandwidth at once. This upgrade increased the VLA's sensitivity by a factor of ~10 and expanded its frequency range from 1–43 GHz to 1–50 GHz. The WIDAR correlator has the raw computing power of thousands of ordinary desktop computers operating in parallel. The resulting data — called "visibilities" — is transformed into images using algorithms developed from mathematical techniques pioneered by radio astronomy in the 1960s.

The Four VLA Configurations: A, B, C, and D

One of the VLA's most distinctive features is its ability to physically move its 27 dishes along 72 km of rail track laid in its Y-shaped arms. This changes the maximum baseline and therefore the resolution and sensitivity of the array. Each configuration is optimised for different science goals.

Config. Max. Baseline Resolution at 6cm Best For Duration
A36.4 km0.3"High resolution: jets, compact sources, masers, exoplanet magnetospheres~4 months/year
B11.1 km1.0"Medium resolution: galaxy morphology, supernova remnants~4 months/year
C3.4 km4.0"Extended emission: HI gas in nearby galaxies, galactic surveys~4 months/year
D1.03 km13"Very extended emission: large angular-scale sources, spectral surveys~4 months/year

The VLA cycles through all four configurations approximately once per year, spending about 4 months in each. Scientists apply for observing time in advance specifying the configuration they need. Moving all 27 antennas between configurations takes approximately 1–3 weeks and is done by a crew using specially designed heavy transport vehicles.

Major VLA Discoveries

Since opening in 1980, the VLA has been involved in an extraordinary range of fundamental discoveries. Here are the most significant:

Binary pulsar gravitational waves — Nobel Prize 1993

Russell Hulse and Joseph Taylor used radio telescopes (including VLA precursor facilities) to monitor the binary pulsar PSR 1913+16 — two neutron stars orbiting each other. Over years of timing observations, they showed that the system's orbital period was decreasing in exact agreement with the rate predicted by general relativity if the system was losing energy to gravitational waves. This was the first indirect proof of gravitational wave emission and won the 1993 Nobel Prize in Physics — decades before LIGO directly detected gravitational waves in 2015.

Active galactic nuclei jets

The VLA's high resolution and radio sensitivity made it the premier instrument for imaging the relativistic jets produced by supermassive black holes in active galaxies. Images of Cygnus A — a radio galaxy 760 million light-years away — revealed twin jets and giant radio lobes in unprecedented detail and became one of the most reproduced images in radio astronomy. VLA studies of jet morphology and motion established the physical mechanisms by which black holes launch and collimate jets of plasma at near-light speeds.

Supernova 1987A radio monitoring

When Supernova 1987A exploded in the Large Magellanic Cloud in February 1987 — the closest supernova visible to the naked eye since 1604 — the VLA was immediately pointed at it and has monitored it continuously ever since. VLA observations tracked the expanding radio shell, observed the shock wave interacting with pre-existing circumstellar material, and provided key data on the rate of energy release. SN 1987A remains one of astronomy's most thoroughly monitored events.

Water megamasers and galaxy distances

Water megamasers are extremely bright radio sources produced by water molecules amplifying microwave radiation in the nuclei of distant galaxies. The VLA has detected and monitored megamasers in numerous galaxies, and through very long baseline interferometry (VLBI), has measured the distances to these galaxies with extraordinary precision — providing an independent measurement of the Hubble constant (rate of cosmic expansion) that doesn't rely on conventional distance "ladder" methods. This remains an active and significant area of VLA science.

Exoplanet radio emission detection

In recent years, the VLA has been at the forefront of detecting radio emission from the magnetospheres of exoplanets — brown dwarfs and giant planets orbiting other stars. Radio emission from a magnetosphere indicates a strong planetary magnetic field, which is significant for habitability (Earth's magnetic field shields the surface from harmful solar wind). This is an active and rapidly developing area of research connecting the VLA to one of astronomy's central questions.

FIRST and NVSS sky surveys

The Faint Images of the Radio Sky at Twenty-centimeters (FIRST) survey mapped 10,000 square degrees of sky, detecting ~946,000 radio sources and creating the definitive radio atlas of the north and south galactic caps. The NRAO VLA Sky Survey (NVSS) covered the sky north of declination −40°, cataloguing 1.8 million radio sources. These surveys are foundational datasets used by thousands of astronomers for statistical studies of galaxy populations, radio source identification, and multi-wavelength cross-matching. The ongoing VLA Sky Survey (VLASS) is the next generation successor, imaging the sky three times over seven years.

Why the VLA Is in the News in 2026

Search interest in the VLA has risen sharply in mid-2026, alongside related searches for radio telescope discoveries. Several developments are driving this:

MeerKAT megamaser discovery

The MeerKAT radio telescope in South Africa (64 dishes, one of the most sensitive radio arrays in the Southern Hemisphere) detected a record-breaking water megamaser at approximately 5 billion light-years — the most distant megamaser yet found, in a galaxy in the process of merging with another. This type of discovery involves collaborative verification across multiple facilities including the VLA, which provides northern hemisphere follow-up observations and VLBI high-resolution imaging. The MeerKAT discovery re-energised public interest in radio astronomy generally and the types of facilities involved.

VLA and JWST joint observations

Astronomers routinely combine James Webb Space Telescope infrared data with VLA radio observations to study star-forming regions, galaxy evolution, and active galactic nuclei across the electromagnetic spectrum. Several high-profile 2026 papers used JWST+VLA multi-wavelength datasets to characterise the earliest galaxies and their radio-loud AGN — results that generated significant press coverage and drove public interest in the underlying facilities.

Next-Generation VLA planning

The astronomy community has been actively planning the Next-Generation VLA (ngVLA) — a proposed facility that would replace the current VLA with ~260 antennas spanning baselines of 1,000 km or more, achieving 10× better sensitivity and resolution. The ngVLA would be transformative for radio astronomy. NSF feasibility studies and preliminary design work are ongoing, and news about the project's progress periodically drives public interest in the current VLA and what it represents.

VLA vs Optical Telescopes: Two Different Universes

The VLA and an optical telescope like the Celestron NexStar 8SE are both "telescopes" in the broadest sense, but they observe completely different portions of the electromagnetic spectrum and reveal completely different aspects of the Universe. Neither is "better" — they are complementary, and combining data from both wavelengths is what produces the most complete picture of any astronomical object.

Property VLA (Radio) Optical Telescope
Wavelength observed1mm – 1m (radio)380–700 nm (visible light)
Can it observe by day?Yes — day and nightMostly night only
Affected by clouds?Mostly no (except mm wavelengths)Yes — clouds block observation
Can see through galactic dust?Yes — radio penetrates dustNo — dust blocks visible light
What it seesJets, pulsars, hydrogen gas, masers, magnetic fieldsStars, planets, nebulae, galaxies by starlight
Detection of planetsRadio emission from magnetospheresReflected sunlight, transits, direct imaging
Cost to useHundreds of millions — professional facilityAccessible — backyard telescopes available to all

Visiting the VLA

The VLA is open to visitors and is one of the most accessible major scientific installations in the United States. The NRAO Visitor Centre at the VLA site offers a self-guided walking tour that lets visitors get very close to the dish antennas (the nearest ones are just metres away from the path), walk along the antenna rail tracks, and visit the control building. Admission is free.

Visit practical information

  • Address: US Highway 60, Datil, New Mexico (50 miles west of Socorro)
  • Hours: Daily 8:30 AM – 4:30 PM (check NRAO website for holiday closures)
  • Admission: Free
  • Nearest town: Socorro, NM (50 miles east) — hotels and restaurants available
  • Duration: Allow 1–2 hours for the full self-guided tour
  • Open house events: NRAO hosts annual Open House (first Saturday in October) with guided tours, demonstrations, and scientist talks

What you'll see at the site

  • The full Y-pattern of dish antennas stretching to the horizon
  • Individual dishes up close — 25 metres tall, clearly enormous
  • Rail tracks and the antenna transporter vehicle
  • Visitor centre with exhibits on radio astronomy and VLA history
  • The control room (visible through windows, scientists working)
  • Vast, dark New Mexico sky — the Milky Way is spectacular from here on clear nights
Night sky observing near the VLA: The Plains of San Agustin where the VLA sits is a designated International Dark Sky area. The skies are among the darkest in the continental United States — Bortle 2–3 class. If you're visiting the VLA by day, consider spending the night nearby for extraordinary naked-eye and telescopic observing. The Milky Way from this site is stunning. See our beginner telescope guide for what to bring.

🔭

Not sure which telescope actually fits your goals?

Answer 5 quick questions about your budget, observing targets, and experience level — our Telescope Finder Tool recommends a specific model in under 2 minutes.

Find My Telescope →

Amateur Radio Astronomy: Getting Involved

The VLA operates at a professional level inaccessible to amateur astronomers — but radio astronomy is not exclusively a professional pursuit. There is a growing amateur radio astronomy community that uses Software Defined Radio (SDR) receivers, modest dish antennas, and specialised software to observe the Sun, Jupiter, meteor radar echoes, and even attempt to detect the 21cm hydrogen line. This is genuinely accessible hobby science.

What amateur radio astronomers observe

  • Solar radio bursts: The Sun produces intense radio emission during solar flares — detectable with relatively modest equipment. Type III bursts can be heard as dramatic crackles in a radio receiver.
  • Jupiter's radio storms: Jupiter's magnetosphere produces powerful radio bursts at 10–40 MHz that can be detected with a simple dipole antenna and a software-defined radio receiver — one of the few active areas where amateur and professional radio astronomy overlap significantly.
  • Meteor radar echoes: Radio waves reflect off the ionised trails left by meteors entering the atmosphere. During meteor showers, dedicated amateur radio setups can count meteor echoes at rates that correlate with ZHR.
  • 21cm hydrogen: With a dedicated hydrogen line receiver and a modest dish (even a surplus dish), detecting galactic hydrogen emission in the Milky Way is achievable from a suburban location.

Why optical telescopes remain the best entry point

For most people inspired by the VLA to start astronomy, an optical telescope — not a radio setup — is the correct first step. Optical telescopes are immediately rewarding: point them at Saturn and you'll see rings on your first night. They require no antenna construction, no signal processing software configuration, and no understanding of radio frequency interference. The VLA's discoveries are inspiring, but the night sky's visual beauty through a 130mm eyepiece is what keeps most amateur astronomers observing for decades.

Consider starting your observing journey with our beginner telescope guide — and if radio astronomy calls to you later, the SARA (Society of Amateur Radio Astronomers) is a dedicated community with resources for new entrants.

Celestron SkyMaster 15x70 binoculars — ideal for dark sky sites like the VLA area

Celestron SkyMaster 15×70 Binoculars — For your VLA site visit

If you're visiting the VLA and want to observe the extraordinary dark sky on the Plains of San Agustin, the SkyMaster 15×70 is the ideal companion. The 70mm aperture gathers enough light to show the Milky Way's structure, star clusters, and even the Andromeda Galaxy in vivid detail from Bortle 2 skies. The 15× magnification keeps the field steady enough for comfortable extended observing when propped against a fence or car roof. This is the binocular we'd bring for a night at the VLA site. Full guide: best astronomy binoculars.

View on Amazon →

Affiliate link. Editorial standards.

VLA Telescope FAQ

What is the VLA telescope and where is it?

The Karl G. Jansky Very Large Array (VLA) is a radio astronomy observatory on the Plains of San Agustin in New Mexico, 50 miles west of Socorro. It consists of 27 dish antennas, each 25 metres in diameter, arranged in a Y-pattern and spread across up to 36 kilometres of rail track. It is operated by the National Radio Astronomy Observatory (NRAO) and has been in operation since 1980. The array works as a single instrument by combining signals from all dishes electronically — a technique called aperture synthesis interferometry.

What has the VLA telescope discovered?

The VLA has been involved in numerous major discoveries: imaging the relativistic jets of Cygnus A and other radio galaxies; continuously monitoring Supernova 1987A since its explosion; detecting water megamasers used to measure the Hubble constant independently; detecting radio emission from exoplanet magnetospheres; completing the FIRST and NVSS sky surveys cataloguing millions of radio sources; and supporting Nobel Prize-winning research on binary pulsars confirming gravitational radiation. It publishes approximately 500+ scientific papers per year.

Can the public visit the VLA telescope?

Yes — the VLA Visitor Centre is open daily from 8:30 AM to 4:30 PM (check NRAO's website for exceptions). Admission is free. A self-guided walking tour takes visitors close to the dish antennas, along the rail tracks, and through exhibits on radio astronomy. The NRAO also holds an annual Open House on the first Saturday of October with guided tours and scientist presentations. The surrounding Plains of San Agustin have exceptional dark skies — Bortle 2–3 — making the area superb for night sky observing.

How does a radio telescope work differently from an optical telescope?

Both detect electromagnetic radiation, but at different wavelengths. Optical telescopes detect visible light (380–700 nm wavelength). Radio telescopes detect radio waves (millimetres to metres). Different physical processes produce these different types of radiation: synchrotron radiation from relativistic electrons in magnetic fields produces radio waves; nuclear fusion in stellar atmospheres produces visible light. Radio waves penetrate dust clouds that block visible light, allowing radio telescopes to observe the Milky Way's centre and deeply embedded star-forming regions invisible to optical telescopes. The VLA combines signals from multiple antennas to achieve the resolution of a telescope 36 km wide through interferometry.

What is the Next-Generation VLA (ngVLA)?

The Next-Generation VLA is a proposed NSF facility that would replace the current VLA with approximately 260 antennas spanning baselines up to 1,000 km or more, achieving 10× better sensitivity and angular resolution than the current array. The ngVLA would transform radio astronomy's ability to study planet formation, the origins of cosmic magnetism, galaxy evolution, and potentially biosignatures. It is in the preliminary design phase as of 2026. The current VLA would likely remain operational alongside the ngVLA in a transitional period.

What is the difference between the VLA and the MeerKAT telescope?

Both are radio interferometric arrays, but they differ in location, size, and design emphasis. The VLA has 27 dishes of 25m diameter in New Mexico; MeerKAT has 64 dishes of 13.5m diameter in the Karoo desert of South Africa. MeerKAT is more sensitive at lower frequencies and is optimised for surveys of the southern sky (including the galactic centre region not well-accessible from New Mexico). MeerKAT is also the core of the eventual Square Kilometre Array (SKA) in Africa. The VLA and MeerKAT are often used collaboratively — MeerKAT makes discoveries in the southern sky that the VLA then follows up with northern hemisphere VLBI high-resolution imaging.




Related Guides

Hubble vs Webb vs Roman Space Telescope

Plain-English comparison of NASA's flagship space observatories — what each sees and why.

Best Binoculars for Stargazing

Perfect for dark-sky sites like the VLA plains — picks from 7x50 to 20x80.

Best Telescopes for Beginners 2026

Inspired by the VLA? Start here for the optical astronomy equivalent.

Night Sky in October 2026

Saturn opposition, Orionids, dark-sky window — the best observing month.

LEGO Hubble Telescope Review

The LEGO space telescope set reviewed — for astronomy fans who love building.

Can You See the Moon Landing Flag?

The physics of telescope resolution — why the Moon's flags are impossible to see from Earth.