The Yerkes Telescope on Williams Bay in Wisconsin, completed in 1897, is the world's largest refractor, with an objective of 101cm. It was financed by Charles Yerkes (who among other things owned large sections of the London Underground before it was nationalized in the 1930s) in response to an appeal from George Ellery Hale, then of Chicago University.
The disadvantages, stopping the construction of larger refractors are
difficulty of supporting the lenses, they tend to distort under their own weight
the thicker the lenses are, the more they absorb light
From 1918 to 1938, the 2.54 meter Hooker reflecting telescope on Mount Wilson (1742 meters), in the vicinity of Pasadena, was the largest telescope in the world. It was originated by the Carnegie Institution of Washington and inaugurated by Hale.
In 1923, Hubble used this telescope to do his groundbreaking work.
It was closed for a time during the 1980s because of light pollution from Los Angeles.
Mount Palomar (1706 meters) is a 5 meter reflector. Designed by Hale. used from 1948.
Las Palmas (Roque de Los Muchachos Observatory), Canary Islands
Altitude of 2332m. Among the telescopes situated here are
- INT - Isaac Newton Telescope
British/Spanish/Dutch - transferred to La Palma from its previous location in Herstmonceux, Sussex. 2.5 m reflecting telescope
- William Herschel Telescope
- Dutch Open Telescope
- Swedish Solar Telescope
- Jacobus Kapetyn Telescope
- William Herschel Telescope
Mauna Kea (White Mountain), Hawaii
A former volcano in Hawaii, with a summit of 4150 meters. The highest observatory in the World. Questions have been asked at a high level as to whether Mauna Kea has too many telecopes atop it (13 by 2000, technically largely if you don't count the arrays as just one telescope)
Keck Actually two telescopes of this name. Whereas the 5 meter Palomar Telescope is the largest reflector with a single mirror, the Keck is effectively a reflector with a 10 meter mirror, although this 'mirror' is made of 36 separate hexagonal segments, aligned by computers. Each of the 36 segments is easy to support and free from distortion.
James Clerk Maxwell Telescope Radio telescope, 15 m across, studying the submillimeter range. Operated by Britain (Edinburgh Observatory), Holland and Canada. Operating since 1986.
UKIRT 3.8 m telescope, run by Edinburgh Observatory. Operating since 1979. Also used for optical research.
Canada-France-Hawaii Telescope Reflector of 3.6m. Optical and Infra Red
Infrared Telescope Facility Run by NASA. 3 meter aperture telescope
Univerity of Hawaii reflector 2.24 meter
Subaru 8 meter 2.24 meter
Smithsonian Astrophysical Observatory Submillimeter Wavelength Array Six parabolic antennas 2.24 meter
- La Silla European - 2350 meters above sea level.
- New Technology Telescope. The first telescope to have 'active optics'.
- VLT - Very Large Telescope. Four identical telescopes each with a mirror of 8.2 meter diameter. Working together, images as good as the Hubble telescope.
- Cerro Tolelo American. Altitude 2200m, near La Serena.
- Las Campanas American. Altitude 2300m on the Cerro Las Campanas, near La Serena. Owned by the Carnegie Institution of Washington.
- Cerro Paranal ESO, four 8-meter telescopes working together to imitate a single 200m telescope. Height 2632 meters.
- Siding Spring
Altitude : 1150m
Opened in 1974, the Anglo-Australian Telescope (AAT) in New South Wales has a size of 3.90m and can be used both in the optical and infra-red. The UK Schmidt telescope is also located there plus a couple of other telescopes
- Mount Stromlo
Launched in 1990 although it proved to have problems which were corrected in 1993. The telescope is a 2.4 meter reflector and it orbits at a height of around 600 km.
Kitt Peak Quinlan Mountains, Arizona. 4 m reflector and the largest instrument in world especially designed for studying the Sun.