Astronomy is all about telescopes. The bigger, the better and there are some very large telescopes currently in use or under construction all around the world. The construction of these monolithic telescopes is all about science and discovery. Many different countries have come together to build some of the biggest, most expensive telescopes ever and everyone benefits.
Large telescopes are not restricted to land based locations alone. Some of the most valuable scientific data comes from medium sized orbiting telescopes, well outside the earths atmosphere and therefore not subject to atmospheric blurring. These telescopes give us some of the most detailed and comprehensive image ever seen of the universe and the Milky Way.
Due to the enormous cost of launching equipment into orbit and the limited space aboard the transportation rocket, there are many limitations when developing a telescope for the space environment. Orbiting observatories must cope with radiation, the cold of space, and a lack of hard line power. This requires implementation of support systems such as solar arrays, radiation shields, and communication systems and they have to be perfect, because there is very little opportunity for repairs in the vastness of space.
Lets break down the 12 largest land and space telescopes.
* = Estimate
#12 Hubble Space Telescope
Aperture: 2.4 m (7.9 ft)
Cost: 2.5 billion USD
Completion Date: April 24, 1990
Type: near-ultraviolet, visible, and near infrared spectra
Location: Low Earth Orbit
Organization: NASA
Website: hubblesite.org
#11 Herschel Space Telescope
Aperture: 3.5 m (11.5 ft)
Cost: €1.1 billion
Completion Date: May 2009
Type: infrared
Location: Space (L2 Region)
Organization: European Space Union
Website: nasa.gov
#10 James Webb Space Telescope (JWST)
Aperture: 6.5 m (21 ft)
Cost: *$8 billion (estimate)
Completion Date: *October 2018 (planned)
Type: Infared
Location: Space (L2 Region)
Organization: NASA
Website: jwst.nasa.gov
#9 Large Synoptic Survey Telescope (LSST)
Aperture: 8.4 m (28 ft)
Cost: *$390 million USD
Completion Date: *2021 (planned)
Type: Three-mirror anastigmat
Location: El Peñón peak, Chile
Organization: LSST Corporation
Website: lsst.org
#8 South African Large Telescope (SALT)
Aperture: 10 m (32.8 ft)
Cost: $30 million USD
Completion Date: 2005
Type: Reflector
Location: 370 km (230 mi) north-east of Cape Town, South Africa
Organization: South African Astronomical Observatory
Website: en.wikipedia.org
#7 Keck I & II Twin Telescopes
Aperture: 10 m (33 ft) each
Cost: $140 million USD
Completion Date: Keck I 1993, Keck II 1996
Type: Reflector
Location: Kamuela, Hawaii
Organization: California Association for Research in Astronomy
Website: keckobservatory.org
#6 Gran Telescopio Canarias (GTC)
Aperture: 10.4 m (34.1 ft)
Cost: €130 million
Completion Date: 2008
Type: Segmented Ritchey-Chrétien telescope
Location: La Palma, Spain
Organization: Instituto de Astrofísica de Canarias, University of Florida, National Autonomous University of Mexico
Website: gtc.iac.es
#5 Giant Magellan Telescope (GMT)
Aperture: 24.5 m (80.4 ft)
Cost: *$700 million - $1 billion USD
Completion Date: *2020 (planned)
Type: Reflector
Location: Las Campanas Observatory, Chile
Organization: GMT Consortium
Website: gmto.org
#4 Thirty Meter Telescope (TMT)
Aperture: 30 m (98 ft)
Cost: *$970 million to $1.2 billion USD
Completion Date: *2022
Type: Segmented Ritchey–Chrétien telescope
Location: Mauna Kea, Hawaii
Organization:
Website: tmt.org
#3 European Extremely Large Telescope (E-ELT)
Aperture: 39.3 m (128.9 ft)
Cost: *€1.055 billion
Completion Date: *early 2020's
Type: Visible, near infrared
Location: Atacama Desert, northern Chile
Organization: European Southern Observatory (ESO)
Website: eso.org
#2 Aricebo Observatory
Aperture: 305 m (1,000 ft)
Cost: $9.3 million
Completion Date: 1963
Type: spherical reflector
Location: Puerto Rico
Organization: SRI International, USRA ,UMET
Website: naic.edu
#1 Five-hundred-meter Aperture Spherical Telescope (FAST)
Aperture: 500 m (1,600 ft)
Cost: *CNY700 million (approx. US$107.9 million)
Completion Date: *September 2016
Type: Spherical Reflector
Location: Pingtang County, Guizhou Province, China
Organization: Chinese Academy of Sciences
Website(forum): skyscrapercity.com