The Biggest Telescopes in the World

The biggest telescope on earth is our window to the stars and into galaxies, far, far away. The world’s largest telescopes are incredibly complex feats of perfectly precise engineering and they give us the phenomenal ability to see back in time as far as the earliest years of our universe. Here are the world’s biggest telescopes.

Building Big
14 January 2022

Objects resembling lenses have been dated to as far back as 2000 BC but it wasn’t until 1608 that Dutch spectacle maker and lens grinder Hans Lippershey submitted (but was denied) a patent for a lens-based viewing instrument ‘for seeing things far away as if they were nearby’.

The first generation of telescopes were primarily used for land-based surveying and military tactics but it was astronomer, physicist and engineer Galileo Galilei who first turned his telescope toward the heavens.

The earliest telescopes had a magnification of just three times normal size but today, the biggest telescopes in the world have the power to unravel the mysteries of the universe, to discover how the universe was formed and to search for habitable worlds beyond our own.

Read on to discover more about the largest telescope in the world and the biggest observatory in the world.

Daniel K. Inouye Solar Telescope

Daniel K. Inouye Solar Telescope at Haleakalā Crater (Photo: Only1BruceC via iStock)

Location: Maui, USA | Mirror Diameter: 4.24 metres | Type: Solar | Cost: £265 million

Named for Hawaiian senator Daniel K. Inouye who died in 2012, it is the largest solar telescope in the world and sits on top of Maui’s 3,055 metre Haleakalā volcano. In 2020 it revealed the turbulent surface of the sun in the highest resolution images ever captured and it will help scientists to understand the mysteries of the sun which date back as far as humankind itself.

James Webb Space Telescope

Engineers and technicians assemble the James Webb Space Telescope (Photo: Alex Wong via Getty Images)

Mirror Diameter: 6.5 metres | Cost: Approx. $10 billion | Weight: 6.5 tons

Equipped with revolutionary technology designed to rewrite what we know about our universe, the James Webb Space Telescope is the most powerful and largest telescope in the world ever launched into space. It was named for James E. Webb, NASA Administrator from 1961 – 1968, and a key player in the Apollo space program which first put men on the moon.

The successor to the Hubble Space Telescope, JWST was launched on Christmas Day 2021 and will orbit one million miles from earth where it will observe the light from the formation of the very first stars and galaxies.

The staggering $10 billion cost of the JWST may seem enourmous, but for context it’s still $1.5 billion less than the cost of the 102.4 mile Danyang-Kunshan Grand Bridge, the longest bridge in the world.

South African Large Telescope

The Southern African Large Telescope (SALT) at the South African Astronomical Observatory (Photo: Mujahid Safodien via Getty Images)

Location: Northern Cape, South Africa | Mirror Diameter: 9.8 metres | Cost: $43 million

The largest optical telescope in the southern hemisphere, SALT is a contender for the biggest telescope on earth and lays claim to be one of the world’s darkest observatory sites. It’s location enables imaging and analysis of astronomical objects that can’t be seen from the northern hemisphere. It was instrumental in revealing one of the universe’s most massive explosions, believed to have shone 570 billion times the brightness of the Sun.

Hobby-Eberly Telescope

Hobby-Eberly Telescope observatory dome at McDonald Observatory (Photo: Stocktrek Images Via Getty Images)

Location: Texas, USA | Mirror Diameter: 10 metres | Altitude: 2,026 metres

Located at the McDonald Observatory in Texas, the Hobby-Eberly is one of the biggest telescopes in the world. In 2012, astronomers used it to measure the mass (almost 17 billion suns) of one of the largest black holes ever discovered, 220 million light-years away in the constellation Perseus.

Keck 1 & Keck 2

Keck I and Keck II Telescopes at the Mauna Kea Observatories at Sunset (Photo: Julie Thurston Photography via Getty Images)

Location: Hawaii, USA | Mirror Diameters: 10 metres | Type: Optical

Perhaps the world’s most famous galactic gazers, the twin telescopes at the WM Keck Observatory atop Hawaii’s dormant Mauna Kea volcano held the joint record for largest telescope in the world when they were built in 1993 and 1996 respectively. Sitting at an altitude of 4,145 metres well above the cloud line, they remain among the world’s most advanced telescopes. The Deep Extragalactic Imaging Multi-Object Spectrograph has the ability to gather light from over 130 galaxies in a single exposure.

Kecks 1 & 2 are also the star attractions at the biggest observatory in the world. They are part of the 17.5 square mile Mauna Kea Science Reserve comprising 12 facilities and 13 telescopes, including the NASA Infrared Telescope Facility built to support the Voyager space missions and the Gemini telescopes which are among the most scientifically advanced and biggest telescopes in the world.

Gran Telescopio Canarias

Observatory on the Roque de los Muchachos, Gran Telescopio Canarias (Photo: Sonja Jordan via Getty Images)

Location: Las Palmas, Spain | Cost: £112 million | Type: Optical | Mirror Diameter: 10.4 metres | Altitude: 2,267 metres

Known locally as GranTeCan, the world’s largest single-aperture optical telescope is the biggest telescope on earth and lives at the Roque de los Muchachos Observatory in the Canary Islands. It’s mirror has a diameter of 10.4 metres and in 2016, the telescope captured an image of galaxy UGC0180, ten times deeper into space than any other telescope had yet achieved, 500 million light-years from Earth.

To Boldly Go…

Later this decade, the 10.4 metre diameter mirror of the GranTeCan will no doubt be dwarfed by telescopes that will see further, deeper and more accurately into space than we can possibly imagine.

The $1 billion Giant Magellan Telescope in Chile is due for completion in 2025 and will have a 24.5 metre mirror and an image resolving power nearly ten times that of Hubble. The Thirty Metre Telescope on Mauna Kea (due for completion in 2027) will allow astronomers to observe the universe without atmospheric disturbances and at 39.3 metres, the European Extremely Large Telescope – able to gather 13 times more light than any other telescope in existence – will be the biggest telescope on earth when it is completed around 2024.

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