Optical telescopic systems are used in astronomy (for observing celestial bodies), in optics for various auxiliary purposes: for example, to change the divergence of laser radiation. The telescope can also be used as a telescope to solve problems of observing distant objects. The very first drawings of a simple lens telescope were discovered in the notes of Leonardo Da Vinci. Built a telescope in Lipperhey. Also, the creation of the telescope is attributed to his contemporary Zachary Jansen.

Story

The year of invention of the telescope, or rather the telescope, is considered to be 1607, when the Dutch spectacle maker John Lippershey demonstrated his invention in The Hague. However, he was refused a patent due to the fact that other masters, such as Zachary Jansen from Middelburg and Jacob Metius from Alkmaar, already possessed copies of telescopes, and the latter, soon after Lippershey, submitted a request to the States General (Dutch parliament) for patent Later research showed that telescopes were probably known earlier, as early as 1605. In his Supplements to Vitellius, published in 1604, Kepler examined the path of rays in an optical system consisting of a biconvex and a biconcave lens. The very first drawings of the simplest lens telescope (both single-lens and double-lens) were discovered in the notes of Leonardo da Vinci, dating back to 1509. His note has been preserved: “Make glass to look at the full moon” (“Atlantic Codex”).

The first person to point a telescope into the sky, turning it into a telescope, and obtain new scientific data, was Galileo Galilei. In 1609, he created his first telescope with three times magnification. In the same year, he built a telescope with eightfold magnification, about half a meter long. Later, he created a telescope that gave a 32-fold magnification: the length of the telescope was about a meter, and the diameter of the lens was 4.5 cm. It was a very imperfect instrument, which had all possible aberrations. Nevertheless, with its help, Galileo made a number of discoveries.

The name "telescope" was proposed in 1611 by the Greek mathematician Ioannis Demisiani (Giovanni Demisiani) for one of Galileo's instruments shown at a country symposium of the Accademia dei Lincei. Galileo himself used the term Lat. for his telescopes. perspicillum.

"Telescope of Galileo", Museum Galileo (Florence)

The 20th century also saw the development of telescopes that operated in a wide range of wavelengths from radio to gamma rays. The first purpose-built radio telescope went into operation in 1937. Since then, a huge variety of sophisticated astronomical instruments have been developed.

Optical telescopes

The telescope is a tube (solid, frame) mounted on a mount, equipped with axes for pointing at and tracking the object of observation. A visual telescope has a lens and an eyepiece. The rear focal plane of the lens is aligned with the front focal plane of the eyepiece. Instead of an eyepiece, photographic film or a matrix radiation receiver can be placed in the focal plane of the lens. In this case, the telescope lens, from the point of view of optics, is a photographic lens, and the telescope itself turns into an astrograph. The telescope is focused using a focuser (focusing device).

According to their optical design, most telescopes are divided into:

  • Lens ( refractors or dioptric) - a lens or lens system is used as a lens.
  • Mirror ( reflectors or cataptric) - a concave mirror is used as a lens.
  • Mirror-lens telescopes (catadioptric) - a spherical primary mirror is usually used as a lens, and lenses are used to compensate for its aberrations.

This can be a single lens (Helmut system), a lens system (Volosov-Galpern-Pechatnikova, Baker-Nana), Maksutov’s achromatic meniscus (systems of the same name), or a planoid aspheric plate (Schmidt, Wright systems). Sometimes the primary mirror is shaped like an ellipsoid (some meniscus telescopes), an oblate spheroid (Wright camera), or simply a slightly shaped irregular surface. This eliminates residual aberrations of the system.

In addition, to observe the Sun, professional astronomers use special solar telescopes, which differ in design from traditional stellar telescopes.

Radio telescopes

Very Large Array radio telescopes in New Mexico, USA

Radio telescopes are used to study space objects in the radio range. The main elements of radio telescopes are a receiving antenna and a radiometer - a sensitive radio receiver, frequency tunable, and receiving equipment. Since the radio range is much wider than the optical range, various designs of radio telescopes are used to record radio emission, depending on the range. In the long-wave region (meter range; tens and hundreds of megahertz), telescopes are used that are composed of a large number (tens, hundreds or even thousands) of elementary receivers, usually dipoles. For shorter waves (decimeter and centimeter range; tens of gigahertz), semi- or fully rotating parabolic antennas are used. In addition, to increase the resolution of telescopes, they are combined into interferometers. When several single telescopes located in different parts of the globe are combined into a single network, they talk about very long baseline radio interferometry (VLBI). An example of such a network is the American VLBA (Very Long Baseline Array) system. From 1997 to 2003, the Japanese orbital radio telescope HALCA operated. Highly Advanced Laboratory for Communications and Astronomy), included in the VLBA network of telescopes, which significantly improved the resolution of the entire network. The Russian orbital radio telescope Radioastron is also planned to be used as one of the elements of the giant interferometer.

Space telescopes

The earth's atmosphere transmits radiation well in the optical (0.3-0.6 microns), near infrared (0.6-2 microns) and radio (1 mm - 30 ) ranges. However, as the wavelength decreases, the transparency of the atmosphere greatly decreases, as a result of which observations in the ultraviolet, X-ray and gamma ranges become possible only from space. An exception is the registration of ultra-high-energy gamma radiation, for which methods of cosmic ray astrophysics are suitable: high-energy gamma photons in the atmosphere generate secondary electrons, which are recorded by ground-based installations using Cherenkov glow. An example of such a system is the CACTUS telescope.

In the infrared range, absorption in the atmosphere is also strong, however, in the region of 2-8 microns there are a number of transparency windows (as in the millimeter range) in which observations can be made. In addition, since most of the absorption lines in the infrared range belong to water molecules, infrared observations can be made in dry regions of the Earth (of course, at those wavelengths where windows of transparency form due to the absence of water). An example of such a telescope placement is the South Pole Telescope. South Pole Telescope), installed at the geographic south pole, operating in the submillimeter range.

In the optical range, the atmosphere is transparent, however, due to Rayleigh scattering, it transmits light of different frequencies differently, which leads to a distortion of the spectrum of luminaries (the spectrum shifts towards red). In addition, the atmosphere is always heterogeneous; currents (winds) constantly exist in it, which leads to image distortion. Therefore, the resolution of Earth-based telescopes is limited to approximately 1 arcsecond, regardless of the telescope aperture. This problem can be partially solved by using adaptive optics, which can greatly reduce the influence of the atmosphere on image quality, and by raising the telescope to a higher altitude, where the atmosphere is thinner - in the mountains, or in the air on airplanes or stratospheric balloons. But the greatest results are achieved when telescopes are taken into space. Outside the atmosphere, distortion is completely absent, so the maximum theoretical resolution of the telescope is determined only by the diffraction limit: φ=λ/D (angular resolution in radians is equal to the ratio of the wavelength to the aperture diameter). For example, the theoretical resolution of a space telescope with a mirror with a diameter of 2.4 meters (like a telescope

Space telescopes

Observing planets, stars, nebulae, and galaxies directly from space - astronomers have dreamed of such an opportunity a long time ago. The fact is that the Earth’s atmosphere, which protects humanity from many cosmic troubles, at the same time prevents observations of distant celestial objects. Cloud cover and instability of the atmosphere itself distort the resulting images, and even make astronomical observations impossible. Therefore, as soon as specialized satellites began to be sent into orbit, astronomers began to insist on launching astronomical instruments into space.

Hubble's firstborn. A decisive breakthrough in this direction occurred in April 1990, when one of the shuttles launched the Hubble telescope weighing 11 tons into space. A unique instrument with a length of 13.1 m and a main mirror diameter of 2.4 m, which cost US taxpayers 1 .2 billion dollars, was named after the famous American astronomer Edwin Hubble, who was the first to notice that galaxies scatter from a certain center in all directions.

The Hubble Space Telescope and its photograph of the pillars of creation - the birth of new stars in the Eagle Nebula

Hubble got off to a rocky start. Two months after it was launched into orbit at an altitude of 613 km, it became obvious that the main mirror was defective. Its curvature at the edges differed from the calculated one by several microns - a fiftieth of the thickness of a human hair. However, even this small amount was enough for Hubble to be nearsighted, and the image it received was blurry.

At first, they tried to correct the image defects on Earth using computer correction programs, but this helped little. Then it was decided to carry out a unique operation to correct “myopia” right in space, by prescribing special “glasses” to Hubble - a corrective optical system.

And so, in the early morning of December 2, 1993, seven astronauts set off on the shuttle Endeavor to carry out a unique operation. They returned to Earth after 11 days, having accomplished the seemingly impossible during five spacewalks - the telescope “received the light.” This became obvious after receiving the next batch of photographs from him. Their quality has increased significantly.

Over the years of its flight, the space observatory has made several tens of thousands of revolutions around the Earth, “winding up” billions of kilometers.

The Hubble telescope has already made it possible to observe more than 10 thousand celestial objects. Two and a half trillion bytes of information collected by the telescope are stored on 375 optical disks. And it still continues to accumulate. The telescope made it possible to discover the existence of black holes in space, revealed the presence of an atmosphere on Jupiter’s satellite Europa, discovered new satellites of Saturn, and allowed us to look into the most remote corners of space...

During the second "inspection" in February 1997, the telescope's high-resolution spectrograph, faint object spectrograph, star pointing device, tape recorder, and solar panel electronics were replaced.

According to the plan, Hubble was supposed to “retire” in 2005. However, it still works properly to this day. Nevertheless, he is already preparing for an honorable resignation. The veteran will be replaced by a new unique space telescope in 2015, named after James Webb, one of the directors of NASA. It was under him that astronauts first landed on the moon.

What does the coming day have in store for us? Since the new telescope will have a composite mirror with a diameter of 6.6 m and a total area of ​​25 square meters. m, it is believed that Webb will be 6 times more powerful than its predecessor. Astronomers will be able to observe objects that glow 10 billion times fainter than the faintest stars visible to the naked eye. They will be able to see the stars and galaxies that witnessed the infancy of the Universe, and also determine the chemical composition of the atmospheres of planets orbiting distant stars.

More than 2,000 specialists from 14 countries are taking part in the creation of the new orbital infrared observatory. Work on the project began back in 1989, when NASA proposed the Next Generation Space Telescope project to the world scientific community. The diameter of the main mirror was planned to be no less than 8 m, but in 2001 ambitions had to be tempered and stopped at 6.6 m - a large mirror does not fit into the Ariane 5 rocket, and the shuttles, as we know, have already stopped flying.

"James Webb" will fly into space under the cover of a "star umbrella". Its shield in the shape of a giant flower will protect the telescope from stellar radiation that makes it difficult to see distant galaxies. Huge umbrella with an area of ​​150 sq. m will consist of five layers of polyamide film, each of which is no thicker than a human hair. For six years, this film was tested for strength, checking whether it could withstand bombardment by micrometeorites. The three inner layers will be covered with an ultra-thin layer of aluminum, and the outer two will be treated with silicon alloy. The sunscreen will function like a mirror, reflecting radiation from the Sun and other luminaries back into space.

As you know, it is so cold in space that in six months the telescope will cool to a temperature below –225 °C. But it is also too high for MIRI, a device for observations in the mid-infrared range (Mid-Infrared Instrument), consisting of a camera, coronagraph and spectrometer. MIRI will have to be further cooled using helium-based refrigeration equipment to a temperature of -266 °C - just 7 °C above absolute zero.

In addition, astronomers tried to find a point in space where the telescope could remain for years, turning its “back” simultaneously to the Earth, Moon and Sun, shielding itself from their radiation with a screen. In a year, which will take one revolution around the Sun, the telescope will be able to survey the entire celestial space.

The disadvantage of this Lagrange libration point L2 is its distance from our planet. So if suddenly some kind of malfunction is discovered in the telescope, as was the case with Hubble, it is unlikely that it will be possible to correct it in the coming years - the repair team now simply has nothing to fly on; new generation ships will appear in five years, not earlier.

This forces scientists, designers and testers, who are now bringing the Webb to condition, to be extremely careful. After all, the Webb telescope will operate at a distance 2,500 times greater than that at which Hubble operated, and almost four times the distance of the Moon from the Earth.

The main mirror, with a diameter of 6.6 m, when assembled, will not fit on any of the existing spacecraft. Therefore, it is made up of smaller parts so that it can be easily folded. As a result, the telescope consists of 18 smaller hexagonal mirrors, with a side length of 1.32 m. The mirrors are made of light and durable beryllium metal. Each of the 18 mirrors, plus three backup ones, weighs about 20 kg. As they say, feel the difference between them and the ton that Hubble's 2.4-meter mirror weighs.

The mirrors are ground and polished with an accuracy of 20 nanometers. The starlight will be reflected by the primary mirror onto a secondary mirror mounted above it, which can be automatically adjusted if necessary. Through the hole in the center of the main mirror, the light will be reflected again - this time onto the instruments.

On Earth, the newly polished mirrors are placed in a giant NASA freezer, where space conditions are created - severe cold and vacuum. By reducing the temperature to -250 °C, specialists must ensure that the mirrors take the expected shape. If not, then they will be polished again, trying to achieve the ideal.

The finished mirrors are then gold-plated, since gold reflects infrared heat rays best. Next, the mirrors will be frozen again and will undergo final testing. Then the telescope will be finally assembled and tested not only for the smooth operation of all components, but also for resistance to vibrations and overloads that are inevitable when launching a rocket into space.

Because gold absorbs the blue portion of the visible light spectrum, the Webb telescope will not be able to photograph celestial objects as they appear to the naked eye. But the ultra-sensitive sensors MIRI, NIRCam, NIRSpec and FGS-TFI can detect infrared light with wavelengths from 0.6 to 28 microns, which will make it possible to photograph the first stars and galaxies formed as a result of the Big Bang.

Scientists suggest that the first stars formed several hundred million years after the Big Bang, and then these giants, with radiation millions of times stronger than the sun, exploded as supernovae. You can check whether this is really so only by looking at the very outskirts of the Universe.

However, the new space telescope is intended not only for observing the most distant and, therefore, ancient objects of the Universe. Scientists are also interested in the dusty regions of the galaxy, where new stars are still being born. Infrared radiation can penetrate dust, and thanks to James Webb, astronomers will be able to understand the formation of stars and their accompanying planets.

Scientists hope not only to capture the planets themselves orbiting stars endless light-years away, but also to analyze the light from Earth-like exoplanets to determine the composition of their atmospheres. For example, water vapor and CO2 send specific signals by which it will be possible to determine whether there is life on planets distant from us.

Radioastron is preparing for work. This space telescope had a difficult fate. Work on it began more than ten years ago, but it was still not possible to complete it - there was no money, overcoming certain technical difficulties required more time than initially thought, or there was another break in space launches...

But finally, in July 2011, the Spektr-R satellite with a payload of about 2600 kg, of which 1500 kg was for the drop-down parabolic antenna, and the rest for the electronic complex containing cosmic radiation receivers, amplifiers, control units, signal converters , scientific data transmission system, etc., was launched.

First, the Zenit-2SB launch vehicle and then the Fregat-2SB upper stage launched the satellite into an elongated orbit around the Earth at an altitude of about 340 thousand km.

It would seem that the creators of the equipment from the Lavochkin NPO, together with the chief designer Vladimir Babyshkin, could breathe freely. But that was not the case!..

“The launch vehicle performed without any problems,” Vladimir Babyshkin said at a press conference. “Then there were two activations of the accelerating block. The orbit of the device is somewhat unusual from the point of view of launch, because there are quite a lot of restrictions that we had to satisfy "...

As a result, both activations of the upper stage took place outside the visibility range of ground stations from Russian territory, and this added excitement to the ground team. Finally, telemetry showed: both the first and second activations went well, all systems worked normally. The solar panels opened, and then the control system kept the device in a given position.

At first, the operation to open the antenna, which consists of 27 petals that were folded during transportation, was scheduled for July 22. The process of opening the petals takes approximately 30 minutes. However, the process did not begin immediately, and the deployment of the radio telescope’s parabolic antenna was completed only on July 23. By autumn, the “umbrella” with a diameter of 10 m was completely opened. “This will make it possible to obtain images, coordinates and angular movements of various objects in the Universe with exceptionally high resolution,” the experts summed up the results of the first stage of the experiment.

After opening the receiving antenna mirror, the space radio telescope takes about three months to synchronize with earth-based radio telescopes. The fact is that it should not work alone, but “in conjunction” with ground-based instruments. It is planned that two hundred-meter radio telescopes in Green Bank, West Virginia, USA, and Effelsberg, Germany, as well as the famous Arecibo radio observatory in Puerto Rico will be used as synchronous radio telescopes on Earth.

Directed simultaneously at the same stellar object, they will work in interferometer mode. That is, to put it simply, with the help of computer information processing methods, the data obtained will be brought together, and the resulting picture will correspond to the one that could be obtained from a radio telescope, the diameter of which would be 340 thousand km larger than the diameter of the Earth.

A ground-space interferometer with such a base will provide conditions for obtaining images, coordinates and angular movements of various objects in the Universe with exceptionally high resolution - from 0.5 milliseconds of arc to several microseconds. “The telescope will have an exceptionally high angular resolution, which will make it possible to obtain previously unattainable in detail images of the space objects being studied,” emphasized RAS Academician Nikolai Kardashev, director of the Academic Space Center of the Lebedev Physical Institute, the lead organization for the complex of scientific equipment of the Radioastron satellite.

By comparison, the resolution that can be achieved using RadioAstron will be at least 250 times higher than that can be achieved using a ground-based network of radio telescopes, and more than 1000 times higher than that of the Hubble Space Telescope operating in optical range.

All this will make it possible to study the surroundings of supermassive black holes in active galaxies, to consider in dynamics the structure of the regions where stars are formed in our Milky Way galaxy; study neutron stars and black holes in our Galaxy; study the structure and distribution of interstellar and interplanetary plasma; build an accurate model of the Earth's gravitational field, as well as carry out many other observations and investigations.

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April 24, 1990 was launched into Earth orbit Hubble orbital telescope, who over almost a quarter of a century of his existence made many great discoveries that shed light on the Universe, its history and secrets. And today we will talk about this orbital observatory, which has become legendary in our time, its history, as well as about some important discoveries made with its help.

History of creation

The idea of ​​placing a telescope where nothing would interfere with its work appeared in the interwar years in the work of the German engineer Hermann Oberth, but the theoretical justification for this was put forward in 1946 by the American astrophysicist Leyman Spitzer. He was so captivated by the idea that he devoted most of his scientific career to its implementation.

The first orbital telescope was launched by Great Britain in 1962, and by the United States of America in 1966. The successes of these devices finally convinced the world scientific community of the need to build a large space observatory capable of looking even into the very depths of the Universe.

Work on the project, which eventually became the Hubble Telescope, began in 1970, but for a long time there was not enough funding to successfully implement the idea. There were periods when the American authorities suspended financial flows altogether.

The limbo ended in 1978, when the US Congress allocated $36 million for the creation of the orbital laboratory. At the same time, active work began on the design and construction of the facility, which involved many research centers and technology companies, a total of thirty-two institutions around the world.


Initially, it was planned to launch the telescope into orbit in 1983, then these dates were postponed to 1986. But the disaster of the Challenger space shuttle on January 28, 1986 forced us to once again revise the launch date of the object. As a result, Hubble launched into space on April 24, 1990 on the Discovery shuttle.

Edwin Hubble

Already in the early eighties, the projected telescope was named in honor of Edwin Powell Hubble, the great American astronomer who made a huge contribution to the development of our understanding of what the Universe is, as well as what astronomy and astrophysics of the future should be like.



It was Hubble who proved that there are other galaxies in the Universe besides the Milky Way, and also laid the foundation for the theory of the Expansion of the Universe.

Edwin Hubble died in 1953, but became one of the founders of the American school of astronomy, its most famous representative and symbol. It is not for nothing that not only the telescope, but also the asteroid is named after this great scientist.

The most significant discoveries of the Hubble telescope

In the nineties of the twentieth century, the Hubble telescope became one of the most famous man-made objects mentioned in the press. Photographs taken by this orbital observatory were printed on the front pages and covers of not only scientific and popular science magazines, but also the regular press, including yellow newspapers.



The discoveries made with the help of Hubble significantly revolutionized and expanded the human understanding of the Universe and continue to do so to this day.

The telescope photographed and sent back to Earth more than a million high-resolution images, allowing one to peer into depths of the Universe that would otherwise be impossible to reach.

One of the first reasons for the media to start talking about the Hubble telescope was its photographs of comet Shoemaker-Levy 9, which collided with Jupiter in July 1994. About a year before the fall, while observing this object, the orbital observatory recorded its division into several dozen parts, which then fell over the course of a week onto the surface of the giant planet.



The size of Hubble (mirror diameter is 2.4 meters) allows it to conduct research in a wide variety of areas of astronomy and astrophysics. For example, it was used to take pictures of exoplanets (planets located outside the solar system), observe the agony of old stars and the birth of new ones, find mysterious black holes, explore the history of the Universe, and also test current scientific theories, confirming or refuting them.

Modernization

Despite the launch of other orbital telescopes, Hubble continues to be the main instrument of stargazers of our time, constantly supplying them with new information from the most distant corners of the Universe.

However, over time, problems began to arise in the operation of Hubble. For example, already in the first week of operation of the telescope, it turned out that its main mirror had a defect that did not allow achieving the expected sharpness of the images. So we had to install an optical correction system on the object directly in orbit, consisting of two external mirrors.



To repair and modernize the Hubble orbital observatory, four expeditions were carried out to it, during which new equipment was installed on the telescope - cameras, mirrors, solar panels and other devices to improve the operation of the system and expand the scope of the observatory.

Future

After the last upgrade in 2009, it was decided that the Hubble telescope will remain in orbit until 2014, when it will be replaced by a new space observatory, the James Webb. But now it is already known that the operational life of the facility will be extended at least until 2018, or even 2020.

Far from the bustle and lights of civilization, in deserted deserts and on mountain tops stand majestic titans, whose gaze is always directed to the starry sky. Some have been standing for decades, while others have only yet to see their first stars. Today we will find out where the 10 largest telescopes in the world are located, and get to know each of them separately.

10. Large Synoptic Survey Telescope (LSST)

The telescope is located on the top of Cero Pachon at an altitude of 2682 m above sea level. By type it belongs to optical reflectors. The diameter of the main mirror is 8.4 m. LSST will see its first light (a term meaning the first use of the telescope for its intended purpose) in 2020. The device will begin to operate fully in 2022. Despite the fact that the telescope is located outside the United States, its construction is funded by the Americans. One of them was Bill Gates, who invested $10 million. In total, the project will cost 400 million.

The main task of the telescope is to photograph the night sky at intervals of several nights. For this purpose, the device has a 3.2 gigapixel camera. LSST has a wide viewing angle of 3.5 degrees. The Moon and the Sun, for example, as seen from Earth, occupy only half a degree. Such wide possibilities are due to the impressive diameter of the telescope and its unique design. The fact is that here, instead of two usual mirrors, three are used. It's not the largest telescope in the world, but it could be one of the most productive.

Scientific goals of the project: search for traces of dark matter; mapping the Milky Way; detection of nova and supernova explosions; tracking small solar system objects (asteroids and comets), in particular those that pass in close proximity to the Earth.

9. South African Large Telescope (SALT)

This device is also an optical reflector. It is located in the Republic of South Africa, on a hilltop, in a semi-desert area near the settlement of Sutherland. The height of the telescope is 1798 m. The diameter of the main mirror is 11/9.8 m.

It is not the largest telescope in the world, but it is the largest in the southern hemisphere. The construction of the device cost 36 million dollars. A third of them were allocated by the South African government. The remainder of the amount was distributed among Germany, Great Britain, Poland, America and New Zealand.

The first photograph of the SALT installation took place in 2005, almost immediately after the completion of construction work. As for optical telescopes, its design is quite non-standard. However, it has become widespread among the newest representatives of large telescopes. The main mirror consists of 91 hexagonal elements, each of which has a diameter of 1 meter. To achieve certain goals and improve visibility, all mirrors can be adjusted in angle.

SALT is designed for spectrometric and visual analysis of radiation emanating from astronomical objects that are beyond the field of view of telescopes located in the northern hemisphere. Telescope employees observe quasars, distant and nearby galaxies, and also track the evolution of stars.

There is a similar telescope in America - Hobby-Eberly Telescope. It is located in the suburbs of Texas and is almost identical in design to the SALT installation.

8. Keck I and II

Two Keck telescopes are connected in a system that creates a single image. They are located in Hawaii on Mauna Kea. is 4145 m. By type, telescopes also belong to optical reflectors.

The Keck Observatory is located in one of the most favorable (from an astroclimate point of view) places on Earth. This means that the interference of the atmosphere in observations is minimal here. Therefore, the Keck Observatory became one of the most effective in history. And this despite the fact that the largest telescope in the world is not located here.

The main mirrors of Keck telescopes are completely identical to each other. They, like the SALT telescope, consist of a complex of moving elements. There are 36 of them for each device. The shape of the mirror is a hexagon. The observatory can observe the sky in the optical and infrared ranges. Keck conducts a wide range of basic research. In addition, it is currently considered one of the most effective ground-based telescopes for searching for exoplanets.

7. Grand Telescope of the Canaries (GTC)

We continue to answer the question of where the largest telescope in the world is located. This time curiosity took us to Spain, to the Canary Islands, or rather to the island of La Palma, where the GTC telescope is located. The height of the structure above sea level is 2267 m. The diameter of the main mirror is 10.4 m. It is also an optical reflector. Construction of the telescope was completed in 2009. The opening was attended by Juan Carlos I, King of Spain. The project cost 130 million euros. 90% of the amount was allocated by the Spanish government. The remaining 10% was divided equally between Mexico and the University of Florida.

The telescope can observe the starry sky in the optical and mid-infrared ranges. Thanks to the Osiris and CanariCam instruments, it can conduct polarimetric, spectrometric and coronagraphic studies of space objects.

6. Arecibo Observatory

Unlike the previous ones, this observatory is a radio reflector. The diameter of the main mirror is (attention!) 304.8 meters. This miracle of technology is located in Puerto Rico at an altitude of 497 m above sea level. And this is not yet the largest telescope in the world. You will find out the name of the leader below.

The giant telescope was caught on camera more than once. Remember the final showdown between James Bond and his adversary in GoldenEye? So she passed right here. The telescope was featured in Carl Sagan's science fiction film Contact and many other films. The radio telescope has also appeared in video games. In particular, in the Rogue Transmission map of the Battlefield 4 toy. The clash between the military takes place around a structure that completely imitates Arecibo.

Arecibo was long believed to be the largest telescope in the world. Every second inhabitant of the Earth has probably seen a photo of this giant. It looks quite unusual: a huge plate placed in a natural aluminum cover and surrounded by dense jungle. A mobile irradiator is suspended above the dish, which is supported by 18 cables. They, in turn, are mounted on three high towers installed along the edges of the plate. Thanks to these dimensions, Arecibo can detect a wide range (wavelength - from 3 cm to 1 m) of electromagnetic radiation.

The radio telescope was put into operation back in the 60s. He appeared in a huge number of studies, one of which was awarded the Nobel Prize. In the late 90s, the observatory became one of the key tools in the project to search for alien life.

5. Great Massif in the Atacama Desert (ALMA)

It's time to take a look at the most expensive ground-based telescope in operation. It is a radio interferometer, which is located at an altitude of 5058 m above sea level. The interferometer consists of 66 radio telescopes, which have a diameter of 12 or 7 meters. The project cost $1.4 billion. It was funded by America, Japan, Canada, Taiwan, Europe and Chile.

ALMA is designed to study millimeter and submillimeter waves. For a device of this kind, the most favorable climate is high-altitude, dry. Telescopes were delivered to the site gradually. The first radio antenna was launched in 2008, and the last one in 2013. The main scientific goal of the interferometer is to study the evolution of the cosmos, in particular the birth and development of stars.

4. Giant Magellan Telescope (GMT)

Closer to the southwest, in the same desert as ALMA, at an altitude of 2516 m above sea level, the GMT telescope with a diameter of 25.4 m is being built. It is an optical reflector. This is a joint project between America and Australia.

The main mirror will include one central and six curved segments surrounding it. In addition to the reflector, the telescope is equipped with a new class of adaptive optics, which allows achieving a minimum level of atmospheric distortion. As a result, the images will be 10 times more accurate than those from the Hubble Space Telescope.

Scientific goals of GMT: search for exoplanets; study of stellar, galactic and planetary evolution; studying black holes and much more. Work on the construction of the telescope should be completed by 2020.

Thirty Meter Telescope (TMT). This project is similar in its parameters and goals to the GMT and Keck telescopes. It will be located on the Hawaiian mountain Mauna Kea, at an altitude of 4050 m above sea level. The diameter of the telescope's main mirror is 30 meters. The TMT optical reflector uses a mirror divided into many hexagonal parts. Only compared to Keck, the dimensions of the device are three times larger. Construction of the telescope has not yet begun due to problems with the local administration. The fact is that Mauna Kea is sacred to the native Hawaiians. The project cost is $1.3 billion. The investment will mainly involve India and China.

3. 50-meter spherical telescope (FAST)

Here it is, the largest telescope in the world. On September 25, 2016, an observatory (FAST) was launched in China, created to explore space and search for signs of intelligent life in it. The diameter of the device is as much as 500 meters, so it received the status of “The world's largest telescope.” China began construction of the observatory in 2011. The project cost the country $180 million. Local authorities even promised that they would resettle about 10 thousand people who live in a 5-kilometer zone near the telescope to create ideal conditions for monitoring.

So Arecibo is no longer the world's largest telescope. China took the title from Puerto Rico.

2. Square Kilometer Array (SKA)

If this radio interferometer project is successfully completed, the SKA observatory will be 50 times more powerful than the largest existing radio telescopes. With its antennas it will cover an area of ​​about 1 square kilometer. The structure of the project is similar to the ALMA telescope, but in terms of dimensions it is significantly larger than the Chilean installation. Today there are two options for the development of events: the construction of 30 telescopes with 200-meter antennas or the construction of 150 90-meter telescopes. In any case, as planned by scientists, the observatory will have a length of 3000 km.

SKA will be located immediately on the territory of two countries - South Africa and Australia. The project cost is about $2 billion. The amount is divided between 10 countries. The project is planned to be completed by 2020.

1. European Extremely Large Telescope (E-ELT)

In 2025, the optical telescope will reach full power, which will exceed the size of the TMT by as much as 10 meters and will be located in Chile on the top of the Cerro Armazones mountain, at an altitude of 3060 m. It will be the largest optical telescope in the world.

Its main almost 40-meter mirror will include almost 800 moving parts, each one and a half meters in diameter. Thanks to such dimensions and modern adaptive optics, E-ELT will be able to find planets like Earth and study the composition of their atmosphere.

The largest reflecting telescope in the world will also study the process of planet formation and other fundamental questions. The project price is about 1 billion euros.

The largest space telescope in the world

Space telescopes do not need the same dimensions as those on Earth, since due to the absence of atmospheric influence they can show excellent results. Therefore, in this case it is more correct to say “the most powerful” rather than “the largest” telescope in the world. Hubble is a space telescope that has become famous throughout the world. Its diameter is almost two and a half meters. Moreover, the resolution of the device is ten times greater than if it were on Earth.

Hubble will be replaced in 2018 by a more powerful one. Its diameter will be 6.5 m, and the mirror will consist of several parts. According to the creators' plans, "James Webb" will be located in L2, in the permanent shadow of the Earth.

Conclusion

Today we got acquainted with ten of the largest telescopes in the world. Now you know how gigantic and high-tech the structures that enable space exploration can be, and also how much money is spent on the construction of these telescopes.

Hubble Space Telescope


Typically, astronomers built their observatories on mountain tops, above the clouds and polluted atmosphere. But even then the image was distorted by air currents. The clearest image is available only from an extra-atmospheric observatory - space.


With a telescope you can see things that are inaccessible to the human eye because the telescope collects more electromagnetic radiation. Unlike a spyglass, which uses lenses to collect and focus light, large astronomical telescopes use mirrors to perform this function.


Telescopes with the largest mirrors should have the best images because they collect the most radiation.


The Hubble Space Telescope is an automatic observatory in orbit around the Earth, named after Edwin Hubble, an American astronomer.

And although Hubble's mirror is only 2.4 meters in diameter - smaller than the largest telescopes on Earth - it can see objects 100 times sharper and details ten times finer than the best ground-based telescopes. And this is because it is above the distorting atmosphere.


The Hubble Telescope is a joint project between NASA and the European Space Agency.


Placing a telescope in space makes it possible to detect electromagnetic radiation in ranges in which the earth’s atmosphere is opaque, primarily in the infrared range.


Due to the absence of atmospheric influence, the resolution of the telescope is 7-10 times greater than a similar telescope located on Earth.


Mars

The Hubble Space Telescope has helped scientists learn a lot about the structure of our galaxy, so it is very difficult to assess its importance for humanity.


One only needs to look at the list of the most important discoveries of this optical device to understand how useful it was, and what an important tool in space exploration it can still be.


Using the Hubble telescope, the collision of Jupiter with a comet was studied, an image of the relief of Pluto was obtained, data from the telescope became the basis for a hypothesis about the mass of black holes located at the center of absolutely every galaxy.


Scientists were able to see auroras on some planets of the solar system, such as Jupiter and Saturn, and many observations and discoveries were made.


Jupiter

The Hubble Space Telescope has peered into another solar system, 25 light-years away from ours, and captured images of several of its planets for the first time.


The Hubble telescope captured images of new planets

In one of the photographs taken in optical, that is, visible light, Hubble captured the planet Fomalhot orbiting the bright star Fomalhot, located 25 light years away from us (about 250 trillion kilometers) in the constellation Southern Pisces.


“The data from Hubble is incredibly important. The light emitted from the planet Fomalhot is a billion times weaker than the light emanating from the star,” commented on the image of the new planet, astronomer from the University of California Paul Kalas. He and other scientists began studying the star Fomalhot back in 2001, when the existence of a planet near the star was not yet known.


In 2004, Hubble sent back to Earth the first images of the regions around the star.


In new images from the Hubble Space Telescope, the astronomer received “documentary” confirmation of his assumptions about the existence of the planet Fomalhot.


Using photographs from the orbital telescope, scientists also “saw” three more planets in the constellation Pegasus.
In total, astronomers have discovered about 300 planets outside our solar system.


But all these discoveries were made on the basis of indirect evidence, mainly through observing the effects of their gravitational fields on the stars around which they orbit.


"Every planet outside our solar system was just a diagram," said Bruce McIntosh, an astrophysicist at the National Laboratory in California. "We've been trying to get pictures of planets for eight years without success, and now we have pictures of several planets at once."


Over 15 years of operation in low-Earth orbit, Hubble received 700 thousand images of 22 thousand celestial objects - stars, nebulae, galaxies, planets.


However, the price that has to be paid for Hubble's achievements is very high: the cost of maintaining a space telescope is 100 times or more higher than a ground-based reflector with a 4-meter mirror.

Already in the first weeks after the telescope began operation in 1990, the resulting images demonstrated a serious problem in the telescope's optical system. Although the image quality was better than that of ground-based telescopes, Hubble could not achieve the desired sharpness, and the resolution of the images was significantly worse than expected.
Image analysis showed that the source of the problem was the incorrect shape of the primary mirror. It was made too flat around the edges. The deviation from the specified surface shape was only 2 micrometers, but the result was catastrophic - an optical defect in which light reflected from the edges of the mirror is focused at a point different from the one at which light reflected from the center of the mirror is focused.
The loss of a significant portion of the light flux significantly reduced the telescope's suitability for observing dim objects and obtaining images with high contrast. This meant that almost all cosmological programs became simply impossible, since they required observations of particularly dim objects.


During the first three years of operation, before the installation of corrective devices, the telescope made a large number of observations. The defect did not have a major effect on the spectroscopic measurements. Despite experiments being canceled due to a defect, many important scientific results were achieved.


Telescope maintenance.


Maintenance of the Hubble telescope is performed by astronauts during spacewalks from reusable spacecraft such as the Space Shuttle.


A total of four expeditions were carried out to service the Hubble telescope.

Due to a defect in the mirror, the first expedition to service the telescope had to install corrective optics on the telescope. The expedition (December 2-13, 1993) was one of the most difficult; five long spacewalks were carried out. In addition, solar panels were replaced, the on-board computer system was updated, and the orbit was corrected.

The second maintenance was carried out on February 11-21, 1997. Research equipment was replaced, the flight recorder was replaced, thermal insulation was repaired, and orbit correction was performed.


Expedition 3A took place December 19-27, 1999. It was decided to carry out some of the work ahead of schedule. This was caused by three of the six guidance system gyros failing. The expedition replaced all six gyroscopes, the precision guidance sensor and the on-board computer.


Expedition 3B (fourth mission) was carried out on March 1-12, 2002. During the expedition, the dim object camera was replaced by an improved survey camera. The solar panels were replaced for the second time. The new panels were one-third smaller in area, which significantly reduced losses due to friction in the atmosphere, but at the same time generated 30% more energy, making simultaneous operation with all instruments installed on board the observatory possible.


The work carried out significantly expanded the capabilities of the telescope and made it possible to obtain images of deep space.


The Hubble telescope is expected to remain in orbit until at least 2013.

Most significant observations

*Hubble provided high-quality images of the 1994 collision of comet Shoemaker-Levy 9 with Jupiter.


* Maps of the surface of Pluto and Eris were obtained for the first time.


* Ultraviolet auroras were observed for the first time on Saturn, Jupiter and Ganymede.


* Additional data on planets outside the solar system, including spectrometric data, were obtained.


* A large number of protoplanetary disks have been found around stars in the Orion Nebula. It has been proven that the process of planet formation occurs in most stars of our Galaxy.


* The theory of supermassive black holes in the centers of galaxies has been partially confirmed; based on observations, a hypothesis has been put forward linking the mass of black holes and the properties of the galaxy.


* the age of the Universe has been updated to 13.7 billion years.