Humans can only see visible light—the portion of the electromagnetic spectrum that is visible to the human eye. That's why so hard to study celestial objects hidden behind cosmic dust. But radio astronomy reveals those parts of the Universe that can't be seen in visible light—and the secrets of dust-shrouded galaxies like our lovely Milky Way.
Objects both on Earth and in space emit other types of detectable electromagnetic radiation, such as radio waves, which penetrate dust. And our beautiful, giant radio telescopes can see those phenomena based on the radio waves they emit. They observe the longest wavelengths of light—ranging from one millimeter to over 10 meters long—and through their sophisticated eyes, we are able to watch stars and planets be born and die, study galaxies and black holes, see the echo of the Big Bang and the Universe’s first galaxies. With arrays of big enough radio telescopes, in the near future astronomers are going to create a much sharper and more detailed map of invisible dark matter—which is estimated to constitute as much as 85 percent of the total matter in the universe.
There are literally hundreds of these radio telescopes scattered all over on Earth, built in all shapes and sizes based on the kind of radio waves they pick up. Here are just 22 of those amazing places from which we scan the universe.
The South Pole Telescope, with a diameter of 30 feet, is located at the Amundsen-Scott South Pole Station, in Antarctica.
The Arecibo Observatory in Puerto Rico is the world's largest and most sensitive single-dish radio telescope.
The Karl G. Jansky Very Large Array radio astronomy observatory is located on the Plains of San Agustin, New Mexico. The observatory consists of 27 independent antennae, each of which has a dish diameter of 75 feet.
The 330-foot diameter Robert C. Byrd telescope in Green Bank, West Virginia, is the world's largest, fully steerable radio telescope. It is also the largest moving object ever built on land.
Here's the Pie Town, New Mexico antenna of the Very Long Baseline Array after a heavy snowstorm. This antenna is one of ten identical 75-foot diameter antennas observing the universe from Hawaii to the U.S. Virgin Islands.
The Atacama Large Millimeter/sub-millimeter Array is an astronomical interferometer of radio telescopes in the Atacama desert of northern Chile, consisting of 66 36-foot and 21-foot diameter radio telescopes.
Photo: ESO/B. Tafresh
The KAT-7 radio telescope on the Northern Cape of South Africa consists of seven dishes of 36 feet in diameter.
Photo: SKA South Africa
Giant Metrewave Radio Telescope, located near Pune in India, is an array of radio telescopes at meter wavelengths.
The 135-foot telescope of the Nobeyama Radio Observatory in Nobeyama, a village in the Japan Alps, sits at an elevation of 4,050 feet.
Photo: Nobeyama Radio Observatory
This is the Siberian Solar Radio Telescope in Khamar-Daban, Irkutsk, Russia. The SSRT is a crossed interferometer, consisting of two arrays of 128x128 parabolic antennas, each 7.5 feet in diameter.
Photo: Sergey Gabdurakhmanov
The Australia Telescope Compact Array is an array of six identical 72-foot diameter dishes, operated by Commonwealth Scientific and Industrial Research Organization at the Paul Wild Observatory.
Photo: David Smyth/CSIRO
Here's the Effelsberg 300-foot Radio Telescope in North Rhine-Westphalia, Germany. For 29 years, it was the largest fully steerable radio telescope on Earth, surpassed by the Robert C. Byrd Green Bank Telescope in 2000.
Photo: Technische Universität Wien
A Perseid meteor streaks across the sky over the Lovell Radio Telescope at Jodrell Bank Observatory, in Holmes Chapel, United Kingdom. The Lovell Telescope was constructed in 1955, when it was the largest steerable dish radio telescope in the world at 228.6 feet in diameter. Now it is the third largest, after the Green Bank telescope, and the Effelsberg telescope in Germany.
Photo: Christopher Furlong/Getty Images
The Swedish-ESO Submillimetre Telescope was a radio telescope with a diameter of 45 feet located at the La Silla Observatory in Chile. It was built in 1987 and decommissioned in 2003.
Photo: Iztok Boncina/ESO
17th October 1972: A farmer driving past five of the eight dishes of the Ryle Telescope at Cambridge, UK.
Photo: Douglas Miller/Keystone/Getty Images
The six 45-foot radio telescopes of the IRAM Interferometer on the Plateau de Bure in the French Alps.
The Sardinia Radio Telescope is a 192-foot diameter, fully steerable radio telescope near San Basilio, in the province of Cagliari in Sardinia, Italy.
The Caltech Submillimeter Observatory is a 31.2-foot diameter submillimeter wavelength telescope situated at Mauna Kea Observatory.
The Combined Array for Research in Millimeter-wave Astronomy is comprised of 23 radio telescopes. The observatory is located in the Inyo Mountains to the east of the Owens Valley Radio Observatory, at a site called Cedar Flat, California.
This is the Large Millimeter Telescope, which sits on top of the Sierra Negra, in Mexico. It has an active surface with a diameter of 150 feet and 2000 m² of collecting area.
The 14-foot diameter Atacama Pathfinder Experiment is located at the Llano de Chajnantor Observatory in the Atacama desert, in northern Chile.
Photo: B. Tafreshi/ESO
Parkes Radio Observatory, Parkes, New South Wales. In the foreground is Austie Helm, from whom CSIRO bought the radio observatory site, mustering a flock of sheep in the paddocks surrounding the telescope. The Parkes Observatory was one of several radio antennas used to receive live, televised images of the Apollo 11 moon landing on July 20, 1969.
Photo: David Moore/CSIRO
Top photo: ALMA by B. Tafreshi/ESO