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Top 10 Biggest Telescopes On Earth 2024

Want to know what are the biggest telescopes on earth in 2024? The largest telescopes in the world are often the most successful in making new space discoveries, because of their ability to gather more light and delve deeper into the history of the universe from impressive distances.

The biggest does not always equate to having the best telescope, and the overall light gathering power of the optical system can be a poor measure of the telescope’s performance. Some of the largest telescopes are serving as Earth’s eyes to detect supernovae, galaxies and other distant objects. Here are the top 10 biggest telescopes on earth that are in operation today and in progress.


Image: Mcdonaldobservatory.org

The 10-metre (30 ft) Hobby–Eberly Telescope (HET) is one of the largest optical telescopes on earth in 2024. It is located at the McDonald Observatory in Davis Mountain, Texas. It was specifically designed for spectroscopy, decoding light from stars and galaxies, studying their properties.

This makes it ideal for discovering planets around other stars, studying distant galaxies, exploding stars, black holes, and more. It includes several features that distinguish it from most telescope designs, resulting in reduced construction costs.

The main mirror of the telescope is mounted at an angle of 55° and can only rotate around its base. A target is tracked by rotating the instruments at the focus of the telescope. Also, it provides access to approximately 70-81% of the sky at its location and allows a target to be tracked for up to two hours.

  • Location: Texas, United States
  • Telescope style: optical telescope, segmented mirror
  • Diameter: 32 feet (10 metres)

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Image: Nasa.gov

The twin Keck Observatory telescopes are the world’s most scientifically productive optical and infrared telescopes. Each telescope weighs 300 tons and operates with nanometer precision. W. M. Keck Observatory is an astronomical observatory with two telescopes at an altitude of 4,145 metres (13,600 ft) near the summit of Mauna Kea in the U.S. state of Hawaii.

Both telescopes have primary mirrors with 10 m (33 ft) apertures, and when completed in 1993 (Keck 1) and 1996 (Keck 2) were the largest optical reflecting telescopes in the world. Keck Observatory is a 501(c)3 supported by both public funding sources and private philanthropy.

The Keck telescopes host a set of state-of-the-art observing instruments and adaptive optics capabilities to collect and analyze astronomical data. The Keck Telescope is one of the largest optical telescopes on earth in 2024.

  • Location: Maunakea, Hawaii
  • Telescope style: astronomical observatory, reflecting telescope
  • Diameter: 32.8 feet (10 metres)


By Pachango – Own work

The Gran Telescopio Canarias is a 10.4 m (410 in) reflecting telescope located at the Roque de los Muchachos Observatory on the island of La Palma in the Canary Islands, Spain. It is the world’s largest single-aperture optical telescope. The Boyes Rock Observatory (ORM, La Palma, Canary Islands) is located in the Northern Hemisphere.

The telescope took seven years to build and cost €130 million. Its installation was hampered by weather conditions and logistical difficulties of transporting equipment to such a remote location. First illumination was achieved in 2007 and scientific observations began in 2009.

The GTC Canary is a Spanish initiative led by the Institute of Astrophysics (IAC). The project is actively supported by the Spanish Government and the local government of the Canary Islands through the European Fund for Regional Development (FEDER) provided by the European Union.

  • Location: La Palma, Spain
  • Telescope style: optical telescope, Ritchey–ChrĂ©tien telescope, segmented mirror
  • Diameter: 34.1 feet (10.4 metres)


Image: Salt.ac.za

The Southern African Large Telescope (SALT) is located at the South African Astronomical Observatory (SAAO) field station near the small town of Sutherland in the Northern Cape province, about 400 km from Cape Town.

SALT is a 9.2-meter optical telescope designed primarily for spectroscopy. It consists of 91 hexagonal mirror segments, each 1-metre in diameter, resulting in a total hexagonal mirror measuring 11.1 by 9.8 metres.

SALT is currently funded by a consortium of international partners from South Africa, the United States, Poland, India and the United Kingdom. The telescope has been in full science operations since 2011 and is realizing its huge potential as Africa’s giant eye on the universe.

  • Location: Karoo, South Africa
  • Telescope style: optical telescope, reflecting telescope, segmented mirror 
  • Diameter: 36 feet (11 metres)


By Iztok BonÄŤina/ESO

The Atacama Large Millimeter/submillimeter Array (ALMA) is an astronomical interferometer of 66 radio telescopes in the Atacama Desert in northern Chile. It observes electromagnetic radiation at millimeter and submillimeter wavelengths.

ALMA is an international partnership between Europe, the United States, Canada, Japan, South Korea, Taiwan, and Chile. Costing approximately US$1.4 billion, it is the most expensive ground-based telescope in operation.

The array is constructed on the Chajnantor Plateau at an altitude of 5,000 metres – near the Llano de Chajnantor Observatory and the Atacama Pathfinder Experiment. This location was chosen for its high altitude and low humidity, which are important for reducing noise and signal attenuation caused by the Earth’s atmosphere.

ALMA began scientific observations in the second half of 2011 and the first images were released to the press on 3 October 2011. The array has been fully operational since March 2013. Collectively known as an astronomical interferometer, each of these antennas work together to produce an image.

  • Location: Atacama desert, Chile
  • Telescope style: Radio interferometer
  • Diameter: 39.4 feet (12 metres)

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one of the biggest telescopes on earth
Nighttime exterior telescope rendering with support site buildings in the foreground. Credit: Giant Magellan Telescope – GMTO Corporation

The Giant Magellan Telescope is a 25.4-metre, ground-based, extremely large telescope under construction at Las Campanas Observatory in the Atacama Desert, Chile. The telescope uses seven of the world’s largest mirrors to create a light gathering area of 368 square metres.

The resolving power of the Giant Magellan Telescope is expected to be 10 times that of the Hubble Space Telescope and four times that of the James Webb Space Telescope, although it will be unable to image in the same infrared frequencies available to telescopes in space. The Giant Magellan Telescope is one of the biggest optical telescopes on earth in 2024.

The Giant Magellan Telescope began casting its primary mirrors in 2005 and began site construction in 2015. The US$2 billion scale telescope is the work of GMTO Corporation, an international consortium of leading research institutions representing six countries: Australia, Brazil, Chile, Israel, South Korea and the United States.

  • Location: Atacama desert, Chile
  • Telescope style: Gregorian telescope 
  • Diameter: 80 feet (24.5 metres)


one of the biggest telescopes on earth
By Courtesy TMT Observatory Corporation

The Thirty Meter Telescope (TMT) is a planned Extremely Large Telescope (ELT). It has become controversial due to its location on Mauna Kea on the island of Hawaii. The TMT will become the largest visible-light telescope on Mauna Kea. Scientists have been considering ELT since the mid-1980s.

Scientists at the University of California, Santa Cruz and Caltech began development of a design that would eventually become the TMT, consisting of a 492-section primary mirror with nine times the power of the Keck Observatory.

Because of its light gathering power and the optimal observing conditions atop Mauna Kea, the TMT will enable astronomers to conduct research that is not possible with current instruments.

The TMT will be the highest of all the proposed ELTs. The telescope receives government support from many countries. The project is currently in progress as part of a collaboration between Japan, the US, Canada, China and India.

  • Location: Mauna Kea, Hawaii
  • Telescope style: Segmented Ritchey–ChrĂ©tien telescope
  • Diameter: 98 feet (30 metres)


one of the biggest telescopes on earth
Composite image of the SKA telescopes, blending real hardware already on site with artist’s impressions. From left: An artist’s impression of the future SKA-Mid dishes blend into the existing precursor MeerKAT telescope dishes in South Africa. From right: An artist’s impression of the future SKA-Low stations blends into the existing AAVS2.0 prototype station in Western Australia.

The Square Kilometre Array (SKA) is an intergovernmental international radio telescope project being built in Australia (low frequency) and South Africa (medium frequency). Chosen for their extremely remote lands, the Karoo region of South Africa and the Murchison Shire of Western Australia are to host the giant radio telescope array.

Australia, where it is initially planned to be home to the largest of these sites, will have 512 telescope stations, while 200 will be located in South Africa. The construction phase of the project began on 5 December 2022 in both South Africa and Australia. SKA is one of the top 10 biggest telescopes on earth in 2024.

The joint infrastructure, the Square Kilometre Array Observatory (SKAO), and headquarters are located at Jodrell Bank Observatory in the United Kingdom. The SKA cores are being built in the southern hemisphere, where views of the Milky Way are best and radio interference is lowest.

  • Location: Australia and South Africa
  • Telescope style: Phased array
  • Diameter: 512 x 49.2 feet (512 x 15 metres) 


one of the biggest telescopes on earth
By Swinburne Astronomy Productions/ESO

The world’s second largest telescope, the Extremely Large Telescope (ELT) is an astronomical observatory under construction. When completed, it will be the world’s largest optical/near-infrared Extremely Large Telescope. The telescope will be encased in a giant, 262-foot (80-metre) high rotating dome that will weigh approximately 6,000 tons.

Part of the European Southern Observatory (ESO) agency, it is located at the top of Cerro Armazon in the Atacama Desert in northern Chile. These include the discovery of Earth-like planets and the search for life beyond the solar system.

The design consists of a reflecting telescope with a 39.3-metre-diameter (130-foot) segmented primary mirror and a 4.2-metre (14 ft) diameter secondary mirror. The telescope will be supported by adaptive optics, six laser guide star units, and several large science instruments.

  • Location: Atacama desert, Chile
  • Telescope style: extremely large telescope, infrared telescope, Nasmyth telescope
  • Diameter: 128 feet (39.3 metres)

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500-METER APERTURE SPHERICAL one of the biggest telescopes on earth
Image: Vajiramias.com

The Five Hundred Meter Aperture Spherical Telescope is a radio telescope located in the Davodang Depression, a natural basin in Pingtang County, Guizhou, southwest China. With a size of 500 metres, it is the largest full-aperture radio telescope in the world by 2024.

FAST has a dish 500 metres (1,600 ft) in diameter built into a natural depression in the landscape. It features a new design using an active surface made of 4,500 metal panels, which form a dynamic parabolic shape in real time.

The cabin with the feed antenna, suspended on cables above the dish, can move automatically using a winch to move the equipment to receive signals from different directions. It observes at wavelengths of 10 cm to 4.3 metres.

  • Location: Guizhou, China
  • Telescope style: radio telescope
  • Diameter: 1,640 feet (500 metres)

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