Largest Telescopes

Radio dish · 500 m

FAST, the Five-hundred-metre Aperture Spherical Telescope in China, is the world's largest single-dish radio telescope, used to study pulsars and fast radio bursts.

Radio dish · 100 m

The Robert C. Byrd Green Bank Telescope in West Virginia is the world's largest fully steerable radio telescope, with a 100-metre dish.

Optical / infrared reflector · 39.3 m

ESO's Extremely Large Telescope, under construction in Chile, will be the world's largest optical/infrared telescope with a 39-metre segmented mirror. It is not yet operational.

Optical / infrared reflector · 30 m

The Thirty Meter Telescope is a planned 30-metre optical/infrared telescope; its site remains the subject of ongoing decisions. It is not yet operational.

Submillimeter dish · 15 m

The James Clerk Maxwell Telescope on Mauna Kea is a 15-metre submillimeter telescope and a station of the Event Horizon Telescope.

Submillimeter dish · 12 m

APEX is a 12-metre submillimeter telescope in the Atacama Desert, a pathfinder for ALMA studying cold dust and gas.

Optical spectroscopic reflector · 11 m

SALT in Sutherland, South Africa is the largest single optical telescope in the Southern Hemisphere, a sibling of the Hobby–Eberly design.

Optical / infrared reflector · 10.4 m

The Gran Telescopio Canarias on La Palma is one of the largest single-aperture optical telescopes in the world, with a 10.4-metre segmented mirror.

Optical / infrared reflector · 10 m

Keck I is one of two 10-metre Keck telescopes on Mauna Kea, using a segmented primary mirror of 36 hexagonal segments.

Optical / infrared reflector · 10 m

Keck II is the second 10-metre Keck telescope, used with adaptive optics for high-resolution near-infrared studies, including the Galactic Centre.

Optical spectroscopic reflector · 10 m

The Hobby–Eberly Telescope at McDonald Observatory in Texas is a 10-metre telescope optimised for spectroscopy, including dark-energy surveys.

Microwave / submillimeter dish · 10 m

The South Pole Telescope is a 10-metre telescope studying the cosmic microwave background and distant galaxy clusters from Antarctica.

Optical / infrared reflector · 8.4 m

The Large Binocular Telescope in Arizona carries two 8.4-metre mirrors on a single mount, giving it the light-gathering power of an 11.8-metre telescope.

Optical / infrared reflector · 8.2 m

ESO's Very Large Telescope at Paranal comprises four 8.2-metre telescopes that can combine as an interferometer; it is among the most scientifically productive observatories on the ground.

Optical / infrared reflector · 8.2 m

The Subaru Telescope, operated by Japan's NAOJ on Mauna Kea, is an 8.2-metre telescope renowned for wide-field imaging.

Optical / infrared reflector · 8.1 m

Gemini North is an 8.1-metre telescope on Mauna Kea, one of the twin Gemini telescopes covering the whole sky.

Optical / infrared reflector · 8.1 m

Gemini South is the 8.1-metre southern Gemini telescope, located on Cerro Pachón in Chile.

Optical / infrared reflector · 6.5 m

The twin 6.5-metre Magellan Telescopes at Las Campanas Observatory in Chile are operated by a US consortium for imaging and spectroscopy.

Near Infrared · 2021

The James Webb Space Telescope is the largest space observatory, observing the infrared universe from the Sun–Earth L2 point.

Optical reflector · 5.1 m

The 200-inch Hale Telescope at Palomar was the largest in the world for decades and remains a workhorse of optical astronomy.