The first telescope was built in 1609 by Italian astronomer Galileo Galilei. The scientist, based on rumors about the invention of the telescope by the Dutch, unraveled its structure and made a sample, which he used for the first time for space observations. Galileo's first telescope had modest dimensions (tube length 1245 mm, lens diameter 53 mm, eyepiece 25 dioptres), imperfect optical design and 30-fold magnification. But it made it possible to make a whole series of remarkable discoveries: discovering the four satellites of the planet Jupiter, the phases of Venus, spots on The sun, mountains on the surface of the moon, the presence of appendages on the disk of Saturn at two opposite points.
More than four hundred years have passed - on earth and even in space, modern telescopes are helping earthlings look into distant cosmic worlds. The larger the diameter of the telescope mirror, the more powerful the optical system.
Multi-mirror telescope
Located on Mount Hopkins, at an altitude of 2606 meters above sea level, in the state of Arizona in the USA. The diameter of the mirror of this telescope is 6.5 meters. This telescope was built back in 1979. In 2000 it was improved. It is called multi-mirror because it consists of 6 precisely adjusted segments that make up one large mirror.
Magellan telescopes
Two telescopes, Magellan-1 and Magellan-2, are located at the Las Campanas Observatory in Chile, in the mountains, at an altitude of 2400 m, the diameter of their mirrors is 6.5 m each. The telescopes began operating in 2002.
And on March 23, 2012, construction began on another more powerful Magellan telescope - the Giant Magellan Telescope; it should go into operation in 2016. In the meantime, the top of one of the mountains was demolished by the explosion to clear a place for construction. The giant telescope will consist of seven mirrors 8.4 meters each, which is equivalent to one mirror with a diameter of 24 meters, for which it has already been nicknamed “Seven Eyes”.
Separated twins Gemini telescopes
Two brother telescopes, each of which is located in a different part of the world. One - "Gemini North" stands on the top of the extinct volcano Mauna Kea in Hawaii, at an altitude of 4200 m. The other - "Gemini South", is located on Mount Serra Pachon (Chile) at an altitude of 2700 m.
Both telescopes are identical, the diameters of their mirrors are 8.1 meters, they were built in 2000 and belong to the Gemini Observatory. Telescopes are located on different hemispheres of the Earth so that the entire starry sky is accessible for observation. Telescope control systems are adapted to work via the Internet, so astronomers do not have to travel to different hemispheres of the Earth. Each of the mirrors of these telescopes is made up of 42 hexagonal fragments that have been soldered and polished. These telescopes are built with the most advanced technologies, making Gemini one of the most advanced astronomical laboratories today.
Northern "Gemini" in Hawaii
Subaru telescope
This telescope belongs to the Japan National Astronomical Observatory. A is located in Hawaii, at an altitude of 4139 m, next to one of the Gemini telescopes. The diameter of its mirror is 8.2 meters. Subaru is equipped with the world's largest “thin” mirror: its thickness is 20 cm, its weight is 22.8 tons. This allows the use of a drive system, each of which transmits its force to the mirror, giving it perfect surface in any position, which allows you to achieve the most best quality images.
With the help of this keen telescope, the most distant galaxy known to date was discovered, located at a distance of 12.9 billion light years. years, 8 new satellites of Saturn, protoplanetary clouds photographed.
By the way, “Subaru” in Japanese means “Pleiades” - the name of this beautiful star cluster.
Japanese Subaru Telescope in Hawaii
Hobby-Eberly Telescope (NO)
Located in the USA on Mount Faulks, at an altitude of 2072 m, and belongs to the MacDonald Observatory. The diameter of its mirror is about 10 m. Despite its impressive size, Hobby-Eberle cost its creators only $13.5 million. We managed to save budget thanks to some design features: the mirror of this telescope is not parabolic, but spherical, not solid - it consists of 91 segments. In addition, the mirror is at a fixed angle to the horizon (55°) and can only rotate 360° around its axis. All this significantly reduces the cost of the design. This telescope specializes in spectrography and is successfully used to search for exoplanets and measure the rotation speed of space objects.
Large South African Telescope (SALT)
It belongs to the South African Astronomical Observatory and is located in South Africa, on the Karoo Plateau, at an altitude of 1783 m. The dimensions of its mirror are 11x9.8 m. It is the largest in the Southern Hemisphere of our planet. And it was made in Russia, at the Lytkarino Optical Glass Plant. This telescope became an analogue of the Hobby-Eberle telescope in the USA. But it was modernized - the spherical aberration of the mirror was corrected and the field of view was increased, thanks to which, in addition to working in spectrograph mode, this telescope is capable of obtaining excellent photographs of celestial objects with high resolution.
The largest telescope in the world ()
It stands on the top of the extinct Muchachos volcano on one of the Canary Islands, at an altitude of 2396 m. Diameter of the main mirror – 10.4 m. Spain, Mexico and the USA took part in the creation of this telescope. By the way, this international project cost 176 million US dollars, of which 51% was paid by Spain.
The mirror of the Grand Canary Telescope, composed of 36 hexagonal parts, is the largest existing in the world today. Although this is the largest telescope in the world in terms of mirror size, it cannot be called the most powerful in terms of optical performance, since there are systems in the world that surpass it in their vigilance.
Located on Mount Graham, at an altitude of 3.3 km, in Arizona (USA). This telescope belongs to the Mount Graham International Observatory and was built with money from the USA, Italy and Germany. The structure is a system of two mirrors with a diameter of 8.4 meters, which in terms of light sensitivity is equivalent to one mirror with a diameter of 11.8 m. The centers of the two mirrors are located at a distance of 14.4 meters, which makes the telescope's resolving power equivalent to 22 meters, which is almost 10 times greater than that of the famous Hubble Space Telescope. Both mirrors of the Large Binocular Telescope are part of the same optical instrument and together form one huge binocular - the most powerful optical instrument in the world at at the moment.
Keck I and Keck II are another pair of twin telescopes. They are located next to the Subaru telescope on the top of the Hawaiian volcano Mauna Kea (height 4139 m). The diameter of the main mirror of each of the Keks is 10 meters - each of them individually is the second largest telescope in the world after the Grand Canary. But this telescope system is superior to the Canary telescope in terms of vigilance. The parabolic mirrors of these telescopes are made up of 36 segments, each of which is equipped with a special computer-controlled support system.
The Very Large Telescope is located in the Atacama Desert in the Chilean Andes, on Mount Paranal, 2635 m above sea level. And it belongs to the European Southern Observatory (ESO), which includes 9 European countries.
A system of four 8.2-meter telescopes, and another four auxiliary 1.8-meter telescopes, is equivalent in aperture to one instrument with a mirror diameter of 16.4 meters.
Each of the four telescopes can work separately, obtaining photographs in which stars up to 30th magnitude are visible. Rarely do all telescopes work at once; it is too expensive. More often, each of the large telescopes works in tandem with its 1.8-meter assistant. Each of the auxiliary telescopes can move on rails relative to its “big brother”, occupying the most advantageous position for observing a given object. The Very Large Telescope is the most advanced astronomical system in the world. A lot of astronomical discoveries were made on it, for example, the world's first direct image of an exoplanet was obtained.
Space Hubble telescope
The Hubble Space Telescope is a joint project of NASA and the European Space Agency, an automatic observatory in Earth orbit, named after the American astronomer Edwin Hubble. The diameter of its mirror is only 2.4 m, which is smaller than the largest telescopes on Earth. But due to the lack of atmospheric influence, the resolution of the telescope is 7 - 10 times greater than a similar telescope located on Earth. Hubble owns many scientific discoveries: collision of Jupiter with a comet, image of Pluto's relief, auroras on Jupiter and Saturn...
Hubble telescope in earth orbit
The first telescopes with a diameter of just over 20 mm and a modest magnification of less than 10x, which appeared at the beginning of the 17th century, made a real revolution in knowledge about the cosmos around us. Today, astronomers are preparing to commission giant optical instruments with a diameter thousands of times larger.
May 26, 2015 became a real holiday for astronomers around the world. On this day, the Governor of the State of Hawaii, David Igay, allowed the start of the zero construction cycle near the top of the extinct volcano Mauna Kea of a giant instrument complex, which in a few years will become one of the largest optical telescopes in the world.
The three largest telescopes of the first half of the 21st century will use different optical designs. The TMT is built according to the Ritchie-Chrétien design with a concave primary mirror and a convex secondary mirror (both hyperbolic). The E-ELT has a concave primary mirror (elliptical) and a convex secondary mirror (hyperbolic). GMT uses a Gregory optical design with concave mirrors: primary (parabolic) and secondary (elliptical).
Giants in the arena
The new telescope is called the Thirty Meter Telescope (TMT) because its aperture (diameter) will be 30 m. If all goes according to plan, the TMT will see first light in 2022, and regular observations will begin another year later. The structure will be truly gigantic - 56 m high and 66 m wide. The main mirror will be made up of 492 hexagonal segments total area 664 m². According to this indicator, TMT will be 80% superior to the Giant Magellan Telescope (GMT) with an aperture of 24.5 m, which will go into operation in 2021 at the Las Campanas Observatory in Chile, owned by the Carnegie Institution.
The thirty-meter telescope TMT is built according to the Ritchie-Chrétien design, which is used in many currently operating large telescopes, including the currently largest Gran Telescopio Canarias with a main mirror with a diameter of 10.4 m. At the first stage, the TMT will be equipped with three IR and optical spectrometers, and in the future it is planned to add several more scientific instruments to them.
However, TMT will not remain world champion for long. The European Extremely Large Telescope (E-ELT), with a record diameter of 39.3 m, is scheduled to open in 2024 and will become the flagship instrument of the European Southern Observatory (ESO). Its construction has already begun at a three-kilometer altitude on Mount Cerro Armazones in the Chilean Atacama Desert. The main mirror of this giant, composed of 798 segments, will collect light from an area of 978 m².
This magnificent triad will form a group of new generation optical supertelescopes that will have no competitors for a long time.
Anatomy of supertelescopes
The optical design of TMT goes back to a system that was independently proposed a hundred years ago by the American astronomer George Willis Ritchie and the Frenchman Henri Chrétien. It is based on a combination of the main concave mirror and a convex mirror of smaller diameter coaxial with it, both of them having the shape of a hyperboloid of revolution. The rays reflected from the secondary mirror are directed into a hole in the center of the main reflector and focused behind it. Using a second mirror in this position makes the telescope more compact and increases its focal length. This design is implemented in many operating telescopes, in particular in the currently largest Gran Telescopio Canarias with a main mirror with a diameter of 10.4 m, in the ten-meter twin telescopes of the Hawaiian Keck Observatory and in the four 8.2-meter telescopes of the Cerro Paranal Observatory, owned by ESO.
The E-ELT optical system also contains a concave primary mirror and a convex secondary mirror, but also has a number of unique features. It consists of five mirrors, and the main one is not a hyperboloid, like the TMT, but an ellipsoid.
GMT is designed completely differently. Its main mirror consists of seven identical monolithic mirrors with a diameter of 8.4 m (six form a ring, the seventh is in the center). The secondary mirror is not a convex hyperboloid, as in the Ritchie-Chrétien design, but a concave ellipsoid located in front of the focus of the primary mirror. In the middle of the 17th century, such a configuration was proposed by the Scottish mathematician James Gregory, and was first put into practice by Robert Hooke in 1673. According to the Gregorian scheme, the Large Binocular Telescope (LBT) was built at the international observatory on Mount Graham in Arizona (both of its “eyes” are equipped with the same primary mirrors as the GMT mirrors) and two identical Magellan telescopes with an aperture of 6.5 m, who have been working at the Las Campanas Observatory since the early 2000s.
The power is in the devices
Any telescope itself is just a very large spotting scope. To turn it into an astronomical observatory, it must be equipped with highly sensitive spectrographs and video cameras.
The TMT, which is designed to have a service life of more than 50 years, will first be equipped with three measuring instruments mounted on a common platform - IRIS, IRMS and WFOS. IRIS (InfraRed Imaging Spectrometer) is a complex of a very high resolution video camera, providing visibility in a field of 34 x 34 arc seconds, and a spectrometer infrared radiation. IRMS is a multi-slit infrared spectrometer and WFOS is a wide-field spectrometer that can simultaneously track up to 200 objects over an area of at least 25 square arcminutes. The design of the telescope includes a flat-rotating mirror that directs light to the devices needed at the moment, and switching takes less than ten minutes. In the future, the telescope will be equipped with four more spectrometers and a camera for observing exoplanets. According to current plans, one additional complex will be added every two and a half years. GMT and E-ELT will also have extremely rich instrumentation.
The supergiant E-ELT will be the world's largest telescope with a main mirror with a diameter of 39.3 m. It will be equipped with a super modern system adaptive optics (AO) with three deformable mirrors capable of eliminating distortions that occur at different altitudes, and wavefront sensors to analyze light from three natural guide stars and four to six artificial ones (generated in the atmosphere using lasers). Thanks to this system, the telescope's resolution in the near-infrared zone, under optimal atmospheric conditions, will reach six milliseconds of arc and will come very close to the diffraction limit caused by the wave nature of light.
European giant
The supertelescopes of the next decade won't come cheap. The exact amount is still unknown, but it is already clear that their total cost will exceed $3 billion. What will these gigantic instruments give to the science of the Universe?
“E-ELT will be used for astronomical observations on a wide range of scales - from solar system to ultra-deep space. And at each scale scale, it is expected to provide exceptionally rich information, much of which cannot be provided by other supertelescopes,” Johan Liske, a member of the scientific team of the European giant, who is involved in extragalactic astronomy and observational cosmology, told Popular Mechanics. “There are two reasons for this: firstly, the E-ELT will be able to collect much more light compared to its competitors, and secondly, its resolution will be much higher. Let's take, say, extrasolar planets. Their list is growing rapidly; by the end of the first half of this year it contained about 2,000 titles. Now the main task is not to increase the number of discovered exoplanets, but to collect specific data about their nature. This is exactly what E-ELT will do. In particular, its spectroscopic equipment will make it possible to study the atmospheres of rocky Earth-like planets with a completeness and accuracy completely inaccessible to currently operating telescopes. This research program involves searching for water vapor, oxygen and organic molecules that may be waste products of terrestrial organisms. There is no doubt that E-ELT will increase the number of candidates for the role of habitable exoplanets."
The new telescope promises other breakthroughs in astronomy, astrophysics and cosmology. As is known, there are considerable grounds for the assumption that the Universe has been expanding for several billion years at an acceleration due to dark energy. The magnitude of this acceleration can be determined from changes in the dynamics of the redshift of light from distant galaxies. According to current estimates, this shift corresponds to 10 cm/s per decade. This value is extremely small to measure using currently operating telescopes, but the E-ELT is quite capable of such a task. Its ultra-sensitive spectrographs will also provide more reliable data to answer the question of whether fundamental physical constants are constant or change over time.
E-ELT promises to revolutionize extragalactic astronomy, which deals with objects beyond the Milky Way. Current telescopes make it possible to observe individual stars in nearby galaxies, but at large distances they fail. The European super telescope will provide an opportunity to see the most bright stars in galaxies distant from the Sun by millions and tens of millions of light years. On the other hand, it will be able to receive light from the earliest galaxies, about which practically nothing is yet known. It will also be able to observe stars near the supermassive black hole at the center of our Galaxy - not only measure their speeds with an accuracy of 1 km/s, but also discover currently unknown stars in the immediate vicinity of the hole, where their orbital speeds approach 10% of the speed of light . And this, as Johan Liske says, is not a complete list unique opportunities telescope.
Magellan telescope
The giant Magellan telescope is being built by an international consortium uniting more than a dozen different universities and research institutes in the USA, Australia and South Korea. As Dennis Zaritsky, professor of astronomy at the University of Arizona and deputy director of the Stuart Observatory, explained to PM, Gregorian optics was chosen because it improves the quality of images over a wide field of view. This optical design is recent years has proven itself well on several optical telescopes in the 6-8 meter range, and even earlier it was used on large radio telescopes.
Despite the fact that GMT is inferior to TMT and E-ELT in terms of diameter and, accordingly, light-gathering surface area, it has many serious advantages. Its equipment will be able to simultaneously measure the spectra of a large number of objects, which is extremely important for survey observations. In addition, GMT optics provide very high contrast and the ability to reach far into the infrared range. The diameter of its field of view, like that of the TMT, will be 20 arc minutes.
According to Professor Zaritsky, GMT will take its rightful place in the triad of future supertelescopes. For example, it will be possible to obtain information about dark matter, the main component of many galaxies. Its distribution in space can be judged by the movement of stars. However, most galaxies where it dominates contain relatively few stars, and rather dim ones. GMT equipment will be able to track the movements of many more of these stars than the instruments of any of the currently operating telescopes. Therefore, GMT will make it possible to more accurately map dark matter, and this, in turn, will make it possible to choose the most plausible model of its particles. This prospect takes on particular value if we consider that until now dark matter has not been detected either by passive detection or obtained at an accelerator. The GMT will also carry out other research programs: the search for exoplanets, including terrestrial planets, the observation of the most ancient galaxies, and the study of interstellar matter.
On earth and in heaven
The James Webb Telescope (JWST) is scheduled to launch into space in October 2018. It will work only in the orange and red zones of the visible spectrum, but will be able to conduct observations in almost the entire mid-infrared range up to waves with a length of 28 microns (infrared rays with wavelengths above 20 microns are almost completely absorbed in the lower layer of the atmosphere by molecules of carbon dioxide and water , so that ground-based telescopes do not notice them). Because it will be protected from thermal interference earth's atmosphere, its spectrometric instruments will be much more sensitive than ground-based spectrographs. However, the diameter of its main mirror is 6.5 m, and therefore, thanks to adaptive optics, the angular resolution of ground-based telescopes will be several times higher. So, according to Michael Bolte, observations from JWST and ground-based supertelescopes will complement each other perfectly. As for the prospects for a 100-meter telescope, Professor Bolte is very cautious in his assessments: “In my opinion, in the next 20-25 years it will simply not be possible to create adaptive optics systems that can effectively work in tandem with a hundred-meter mirror. Perhaps this will happen in about forty years, in the second half of the century.”
Hawaiian project
“TMT is the only one of the three future supertelescopes for which a site has been selected in the Northern Hemisphere,” says Michael Bolte, a member of the board of directors of the Hawaiian project and a professor of astronomy and astrophysics at the University of California, Santa Cruz. “However, it will be mounted not very far from the equator, at 19 degrees north latitude. Therefore, it, like other telescopes at the Mauna Kea Observatory, will be able to survey the sky of both hemispheres, especially since this observatory is one of the best places on the planet in terms of observation conditions. In addition, the TMT will work in conjunction with a group of nearby telescopes: the two 10-meter twins Keck I and Keck II (which can be considered prototypes of the TMT), as well as the 8-meter Subaru and Gemini-North. It is no coincidence that the Ritchie-Chrétien system is used in the design of many large telescopes. She provides good field vision and very effectively protects against both spherical and comatic aberration, which distorts images of objects that do not lie on the optical axis of the telescope. Plus, there are some truly great adaptive optics planned for the TMT. It is clear that astronomers rightly expect that observations at the TMT will yield many exciting discoveries.”
According to Professor Bolte, both TMT and other supertelescopes will contribute to the progress of astronomy and astrophysics, primarily by once again pushing back the boundaries of the known universe in both space and time. Just 35-40 years ago, observable space was mainly limited to objects no older than 6 billion years. It is now possible to reliably observe galaxies about 13 billion years old, whose light was emitted 700 million years after the Big Bang. There are candidates for galaxies with an age of 13.4 billion years, but this has not yet been confirmed. We can expect that TMT instruments will be able to detect light sources that are only slightly younger (100 million years) than the Universe itself.
TMT will provide astronomy and many other opportunities. The results that will be obtained from it will make it possible to clarify the dynamics of the chemical evolution of the Universe, to better understand the processes of formation of stars and planets, to deepen knowledge about the structure of our Galaxy and its closest neighbors and, in particular, about the galactic halo. But the main point is that TMT, like GMT and E-ELT, is likely to allow researchers to answer questions of fundamental importance that are currently impossible not only to formulate correctly, but even to imagine. This, according to Michael Bolte, is the main value of supertelescope projects.
10 largest telescopes
Far from the lights and noise of civilization, on the tops of mountains and in deserted deserts live titans, whose multi-meter eyes are always turned to the stars.
We have selected 10 of the largest ground-based telescopes: some have been contemplating space for many years, others have only yet to see the “first light”.
10.Large Synoptic Survey Telescope
Main mirror diameter: 8.4 meters
Location: Chile, peak of Mount Cero Pachon, 2682 meters above sea level
Type: reflector, optical
Although LSST will be located in Chile, it is a US project and its construction is entirely financed by Americans, including Bill Gates (who personally contributed $10 million of the required $400).
The purpose of the telescope is to photograph the entire available night sky every few nights; for this purpose, the device is equipped with a 3.2 gigapixel camera. LSST features a very wide viewing angle of 3.5 degrees (by comparison, the Moon and Sun as seen from Earth occupy only 0.5 degrees). Such capabilities are explained not only by the impressive diameter of the main mirror, but also by the unique design: instead of two standard mirrors, LSST uses three.
Among the scientific goals of the project are the search for manifestations of dark matter and dark energy, mapping the Milky Way, detecting short-term events such as nova or supernova explosions, as well as registering small solar system objects such as asteroids and comets, in particular, near Earth and in the Kuiper Belt.
LSST is expected to see “first light” (a common Western term meaning the moment when the telescope is first used for its intended purpose) in 2020. Construction is currently underway, and the device is scheduled to become fully operational in 2022.
Large Synoptic Survey Telescope, concept
9. South African Large Telescope
Main mirror diameter: 11 x 9.8 meters
Location: South Africa, hilltop near the settlement of Sutherland, 1798 meters above sea level
Type: reflector, optical
The largest optical telescope in the southern hemisphere is located in South Africa, in a semi-desert area near the city of Sutherland. A third of the $36 million needed to build the telescope was contributed by the South African government; the rest is divided between Poland, Germany, Great Britain, the USA and New Zealand.
SALT took its first photo in 2005, shortly after construction was completed. Its design is quite unusual for optical telescopes, but is common among the latest generation of “very large telescopes”: the primary mirror is not single and consists of 91 hexagonal mirrors with a diameter of 1 meter, the angle of each of which can be adjusted to achieve a specific visibility.
Designed for visual and spectrometric analysis of radiation from astronomical objects that are inaccessible to telescopes in the northern hemisphere. SALT employees observe quasars, nearby and distant galaxies, and also monitor the evolution of stars.
There is a similar telescope in the States, it is called the Hobby-Eberly Telescope and is located in Texas, in the town of Fort Davis. Both the mirror diameter and its technology are almost exactly the same as SALT.
South African Large Telescope
8. Keck I and Keck II
Main mirror diameter: 10 meters (both)
Location: USA, Hawaii, Mauna Kea mountain, 4145 meters above sea level
Type: reflector, optical
Both of these American telescopes are connected into one system (astronomical interferometer) and can work together to create a single image. The telescopes' unique location in one of the best locations on Earth for astroclimate (the degree to which the atmosphere interferes with the quality of astronomical observations) has made Keck one of the most efficient observatories in history.
The main mirrors of Keck I and Keck II are identical to each other and are similar in structure to the SALT telescope: they consist of 36 hexagonal moving elements. The observatory's equipment makes it possible to observe the sky not only in the optical, but also in the near-infrared range.
In addition to being a major part of the widest range of research, Keck is currently one of the most effective ground-based instruments in the search for exoplanets.
Keck at sunset
7. Gran Telescopio Canarias
Main mirror diameter: 10.4 meters
Location: Spain, Canary Islands, La Palma island, 2267 meters above sea level
Type: reflector, optical
Construction of the GTC ended in 2009, at which time the observatory was officially opened. Even the King of Spain, Juan Carlos I, came to the ceremony. A total of 130 million euros were spent on the project: 90% was financed by Spain, and the remaining 10% was equally divided by Mexico and the University of Florida.
The telescope is capable of observing stars in the optical and mid-infrared range, and has CanariCam and Osiris instruments, which allow GTC to conduct spectrometric, polarimetric and coronagraphic studies of astronomical objects.
Gran Telescopio Camarias
6. Arecibo Observatory
Main mirror diameter: 304.8 meters
Location: Puerto Rico, Arecibo, 497 meters above sea level
Type: reflector, radio telescope
One of the most recognizable telescopes in the world, the Arecibo radio telescope has been captured on more than one occasion by movie cameras: for example, the observatory appeared as the site of the final confrontation between James Bond and his antagonist in the film GoldenEye, as well as in the sci-fi film adaptation of Karl's novel Sagan "Contact".
This radio telescope even found its way into video games - in particular, in one of the Battlefield 4 multiplayer maps, called Rogue Transmission, a military clash between two sides takes place right around a structure completely copied from Arecibo.
Arecibo looks really unusual: a giant telescope dish with a diameter of almost a third of a kilometer is placed in a natural karst sinkhole, surrounded by jungle, and covered with aluminum. A movable antenna feed is suspended above it, supported by 18 cables from three high towers at the edges of the reflector dish. The giant structure allows Arecibo to catch electromagnetic radiation relatively large range - with a wavelength from 3 cm to 1 m.
Commissioned back in the 60s, this radio telescope has been used in countless studies and has helped make a number of significant discoveries (like the first asteroid discovered by the telescope, 4769 Castalia). Arecibo once even provided scientists with a Nobel Prize: in 1974, Hulse and Taylor were awarded for the first ever discovery of a pulsar in a binary star system (PSR B1913+16).
In the late 1990s, the observatory also began to be used as one of the instruments of the American SETI project to search for extraterrestrial life.
Arecibo Observatory
5. Atacama Large Millimeter Array
Main mirror diameter: 12 and 7 meters
Location: Chile, Atacama Desert, 5058 meters above sea level
Type: radio interferometer
At the moment, this astronomical interferometer of 66 radio telescopes of 12 and 7 meters in diameter is the most expensive operating ground-based telescope. The USA, Japan, Taiwan, Canada, Europe and, of course, Chile spent about $1.4 billion on it.
Since the purpose of ALMA is to study millimeter and submillimeter waves, the most favorable climate for such a device is dry and high-altitude; this explains the location of all six and a half dozen telescopes on the desert Chilean plateau 5 km above sea level.
The telescopes were delivered gradually, with the first radio antenna becoming operational in 2008 and the last in March 2013, when ALMA was officially launched at its full planned capacity.
The main scientific goal of the giant interferometer is to study the evolution of space at the earliest stages of the development of the Universe; in particular, the birth and subsequent dynamics of the first stars.
ALMA radio telescopes
4. Giant Magellan Telescope
Main mirror diameter: 25.4 meters
Location: Chile, Las Campanas Observatory, 2516 meters above sea level
Type: reflector, optical
Far southwest of ALMA, in the same Atacama Desert, another large telescope is being built, a project of the United States and Australia - GMT. The main mirror will consist of one central and six symmetrically surrounding and slightly curved segments, forming a single reflector with a diameter of more than 25 meters. In addition to a huge reflector, the telescope will be equipped with the latest adaptive optics, which will eliminate as much as possible the distortions created by the atmosphere during observations.
Scientists expect these factors will allow GMT to produce images 10 times sharper than Hubble's, and likely even better than its long-awaited successor, the James Webb Space Telescope.
Among the scientific goals of GMT is a very wide range of research - searching for and photographing exoplanets, studying planetary, stellar and galactic evolution, studying black holes, manifestations of dark energy, as well as observing the very first generation of galaxies. The operating range of the telescope in connection with the stated purposes is optical, near and mid-infrared.
All work is expected to be completed by 2020, but it is stated that GMT can see the “first light” with 4 mirrors as soon as they are introduced into the design. Currently, work is underway to create a fourth mirror.
Giant Magellan Telescope Concept
3. Thirty Meter Telescope
Main mirror diameter: 30 meters
Location: USA, Hawaii, Mauna Kea mountain, 4050 meters above sea level
Type: reflector, optical
The TMT is similar in purpose and performance to the GMT and Hawaiian Keck telescopes. It is on the success of Keck that the larger TMT is based, with the same technology of a primary mirror divided into many hexagonal elements (only this time its diameter is three times larger), and the stated research goals of the project almost completely coincide with the tasks of the GMT, right down to photographing the earliest galaxies almost at the edge of the Universe.
The media cite different project costs, ranging from $900 million to $1.3 billion. It is known that India and China have expressed their desire to participate in TMT and agree to take on part of the financial obligations.
At the moment, a place for construction has been chosen, but there is still opposition from some forces in the Hawaiian administration. Mauna Kea is a sacred site for Native Hawaiians, and many of them are categorically against the construction of an ultra-large telescope.
It is assumed that all administrative problems will be resolved very soon, and construction is planned to be completely completed around 2022.
Thirty Meter Telescope Concept
2. Square Kilometer Array
Main mirror diameter: 200 or 90 meters
Location: Australia and South Africa
Type: radio interferometer
If this interferometer is built, it will become 50 times more powerful astronomical instrument than the largest radio telescopes on Earth. The fact is that SKA must cover an area of approximately 1 square kilometer with its antennas, which will provide it with unprecedented sensitivity.
In structure, SKA is very similar to the ALMA project, however, in size it will significantly exceed its Chilean counterpart. At the moment there are two formulas: either build 30 radio telescopes with antennas of 200 meters, or 150 with a diameter of 90 meters. One way or another, the length over which the telescopes will be placed will be, according to scientists’ plans, 3000 km.
To choose the country where the telescope will be built, a kind of competition was held. Australia and South Africa reached the finals, and in 2012 a special commission announced its decision: the antennas would be distributed between Africa and Australia in common system, that is, the SKA will be deployed on the territory of both countries.
The declared cost of the megaproject is $2 billion. The amount is divided between a number of countries: Great Britain, Germany, China, Australia, New Zealand, the Netherlands, South Africa, Italy, Canada and even Sweden. It is expected that construction will be fully completed by 2020.
Artist's rendering of the 5 km SKA core
1. European Extremely Large Telescope
Main mirror diameter: 39.3 meters
Location: Chile, top of Cerro Armazones mountain, 3060 meters
Type: reflector, optical
For a couple of years - perhaps. However, by 2025, a telescope will reach full capacity, which will exceed the TMT by a whole ten meters and which, unlike the Hawaiian project, is already under construction. We are talking about the undisputed leader among the newest generation of large telescopes, namely the European Very Large Telescope, or E-ELT.
Its main almost 40-meter mirror will consist of 798 moving elements with a diameter of 1.45 meters. This, together with the most modern adaptive optics system, will make the telescope so powerful that, according to scientists, it will not only be able to find planets similar to Earth in size, but will also be able to use a spectrograph to study the composition of their atmosphere, which opens up completely new prospects in the study planets outside the solar system.
In addition to searching for exoplanets, E-ELT will study the early stages of cosmic development, try to measure the exact acceleration of the expansion of the Universe, and test physical constants for, in fact, constancy over time; Also, this telescope will allow scientists to dive deeper than ever into the processes of planet formation and their primary chemical composition in search of water and organic matter - that is, E-ELT will help answer a number of fundamental scientific questions, including those affecting the origin of life.
The cost of the telescope declared by representatives of the European Southern Observatory (the authors of the project) is 1 billion euros.
European Extremely Large Telescope Concept
Size comparison of E-ELT and Egyptian pyramids
Hello, comrades. I'll tell you something, mostly wasted objects and trash heaps. Let's visit an active facility - a real astrophysical observatory with a huge telescope.
So, here it is, a special astrophysical observatory Russian Academy Sciences, known as object code 115.
It is located in the North Caucasus at the foot of Mount Pastukhovaya in the Zelenchuk region of the Karachay-Cherkess Republic of Russia (Nizhny Arkhyz village and Zelenchukskaya village). Currently, the observatory is the largest Russian astronomical center for ground-based observations of the Universe, which has large telescopes: the six-meter optical reflector BTA and the RATAN-600 ring radio telescope. Founded in June 1966. 
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This gantry crane was used to build the observatory.
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For more details, you can read http://www.sao.ru/hq/sekbta/40_SAO/SAO_40/SAO_40.htm here. 
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The observatory was created as a center for collective use to support the operation of the BTA optical telescope (Large Azimuthal Telescope) with a mirror diameter of 6 meters and the RATAN-600 radio telescope with a ring antenna diameter of 600 meters, then the world's largest astronomical instruments. They were commissioned in 1975-1977 and are designed to study objects in near and deep space using ground-based astronomy methods. 
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Looking at this futuristic door you just want to go inside and feel all the power. 
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Here we are inside. 
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We have an old control panel in front of us. Apparently it doesn't work. 
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Here comes the most interesting part. BTA - "Large Azimuth Telescope". This marvel has been the largest telescope in the world since 1975, when it surpassed Palomar Observatory's 5-meter Hale Telescope, until 1993, when the Keck Telescope with a 10-meter segmented mirror became operational.
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Yes, 
this same Keck.
The BTA is a reflecting telescope. The main mirror with a diameter of 605 cm has the shape of a paraboloid of rotation. The focal length of the mirror is 24 meters, the weight of the mirror excluding the frame is 42 tons. The optical design of the BTA provides for operation in the main focus of the main mirror and two Nesmith focuses. In both cases, an aberration corrector can be used.
The telescope is mounted on an alt-azimuth mount. The mass of the moving part of the telescope is about 650 tons. The total mass of the telescope is about 850 tons.
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Chief designer - Doctor of Technical Sciences Bagrat Konstantinovich Ioannisiani (LOMO). 
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The optical system of the telescope was manufactured at the Leningrad Optical-Mechanical Association named after. V.I. Lenin (LOMO), Lytkarino Optical Glass Plant (LZOS), State Optical Institute named after. S. I. Vavilova (GOI).
For its production, even separate workshops were built that had no analogues.
Do you know what?
- The blank for the mirror, cast in 1964, cooled for more than two years.
- 12,000 carats of natural diamonds in powder form were used to process the workpiece, processing grinding machine, manufactured at the Kolomna Heavy Machine Tool Plant, was carried out for 1.5 years.
- The mass of the blank for the mirror was 42 tons.
- In total, the creation of a unique mirror lasted for 10 years.
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The main mirror of the telescope is subject to temperature deformation, like all huge telescopes of this type. If the temperature of the mirror changes faster than 2° per day, the resolution of the telescope drops by one and a half times. Therefore, special air conditioners are installed inside to maintain optimal temperature regime. It is forbidden to open the telescope dome if the temperature difference between the outside and inside of the tower is more than 10°, since such temperature changes can lead to destruction of the mirror. 
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Plumb 
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Unfortunately, the North Caucasus is not the most best place for such a megadevice. The fact is that in mountains open to all winds there is very high atmospheric turbulence, which significantly impairs visibility and does not allow using the full power of this telescope. 
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On May 11, 2007, transportation of the first main mirror of the BTA began to the Lytkarino Optical Glass Plant (LZOS), which manufactured it, for the purpose of deep modernization. The telescope now has a second primary mirror installed. After processing in Lytkarino - removing 8 millimeters of glass from the surface and repolishing, the telescope should be among the ten most accurate in the world. The modernization was completed in November 2017. Installation and start of research are planned for 2018. 
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I hope you enjoyed the walk. Let's go out. 
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