The Hubble Space Telescope (which is often referred to as HST) is an international collaboration project between NASA and the European Space Agency, which was launched into the near-Earth orbit by the space shuttle Discovery on April 24, 1990 (May 4, 1369) and after 31 Sal continues his mission. Hubble was not the first space telescope to successfully orbit, But it was bigger and better equipped than its fellows, and its amazing discoveries completely changed the human vision of the universe.

Hubble is orbiting about 547 km above the Earth’s surface. Its length is 13.2 meters, which is the size of a big bus, and its weight is 12,200 kilograms, which is the size of two adult elephants. Hubble uses solar energy and moves at about 8 kilometers per second to stay in orbit.

The Hubble telescope takes very high-resolution images of celestial bodies such as planets, stars, and galaxies, and has recorded more than 1.5 million galaxy observations. These observations include detailed images of the birth and death of stars, galaxies billions of light-years away, and remnants of comets that hit planets’ atmospheres.

Hubble was developed as a general-purpose space observatory with the aim of exploring the universe and recording images in visible, ultraviolet, and infrared wavelengths. So far, this telescope has studied more than 40,000 cosmic objects and has provided high-resolution and detailed images to astronomers who could not see them from Earth.

In addition to blocking some wavelengths of light completely, the Earth’s atmosphere contains air currents that are constantly moving and cause the stars to twinkle in the night sky. The constant movement of these air currents blurs the images taken by ground-based telescopes; For this reason, it was necessary to place a telescope in an orbit above the atmosphere to record images free of these effects.

Hubble’s mirror is much smaller than that found in the largest ground-based observatories, But the unique position of this telescope above the Earth’s atmosphere gives extraordinary clarity to the recorded images. As this telescope rotates around the earth, the mirror collects the cosmic lights and transmits them to the earth in the form of images and data. To photograph some of the most distant objects in the sky, the telescope stares at a point in the galaxy for days to capture as much of this very faint glow as possible.

The Hubble Space Telescope takes its name from Edwin Hubble, a famous American astronomer, whose observations showed scientists that there are other galaxies in the universe besides the Milky Way. While working at the Mount Wilson Observatory in 1923, Hubble concluded that Andromeda then considered a nebula, was actually an independent galaxy hundreds of thousands of light-years away from the Milky Way.

Also, in 1929, by discovering that galaxies are moving away from each other at a constant speed, he put a stamp on the “static universe” theory and thus laid the foundation for the Big Bang theory. Edwin Hubble died in 1929, But the telescope that bears his name has since confirmed and modified many of his theories.

Of course, the idea of ​​building a space telescope dates back to 1946; That is, more than 10 years before the establishment of NASA. It was in that year that astrophysicist Lyman Spitzer Jr. wrote an influential paper on the merits of a space-based observatory. In this paper, he argued that an orbiting telescope could observe the sky without encountering the Earth’s atmosphere, which blurs the images and records very high-resolution images.

Spitzer was later instrumental in building the four unmanned Orbiting Astronomical Observatory satellites that NASA launched between 1966 and 1972 and tirelessly petitioned the US government for funding to build a bigger and better space telescope. The huge costs of this project were a big obstacle to its realization, and it was only in 1977 that the American Congress finally agreed to allocate funds for the construction of the telescope, which was named Hubble.

The fledgling Hubble project suffered a major blow in 1986 when the space shuttle Challenger exploded during takeoff, killing seven astronauts. Following this tragic disaster, NASA grounded its space fleet and left Hubble, which needed a shuttle for transportation and repairs, without a vehicle. Of course, scientists made good use of this opportunity and improved the sensitivity of the telescope instruments and improved its ground control software; But these years of delay imposed huge costs on NASA to service and maintain Hubble in a clean and advanced room. When the space shuttle Discovery finally launched Hubble in 1990, the project was seven years behind schedule and over $1 billion over budget.

Unfortunately, this was not the end of Hubble’s problems. That same year, when NASA scientists viewed the first images recorded by Hubble, they discovered that its primary mirror had been polished to the wrong specification. This “spherical deviation” was very small; In fact, less than 1/50 of the width of a human hair; But this slight deviation was enough to blur many Hubble pictures.

Within months, the telescope had become something of a national joke, with one Newsweek magazine even calling it a “$1.5 billion mistake.” NASA had to wait until December 1993 to experience good things; That is when a group of scientists installed a contact lens called COSTAR on Hubble to fix this deviation. Consisting of several small mirrors, Quastar captured the beam emitted by the defective mirror, corrected the defect, and then reflected the corrected beam back to the center of the mirror for analysis.

Hubble’s “space glasses” managed to solve the problem of blurred images, and soon after this telescope began to record amazing images of the universe. Of course, today all the instruments installed in Hubble have internal corrective optics to compensate for mirror defects, and COSTAR is no longer needed.

When the Hubble telescope was launched, it was at a height of 547 km from the earth’s surface; But most of the time it orbits the earth at an altitude of 320 km and sometimes it rises to an altitude of 400 km to visit the International Space Station.

Currently, Hubble’s nearly circular orbit is located at an altitude of 550 km from the Earth’s surface, and each revolution of this telescope takes about 96 minutes. In this way, Hubble goes around the earth 15 times a day; But not everyone can see it in the sky.

Hubble is best seen in regions on Earth between latitudes 28.5 degrees north and 28.5 degrees south. The reason is that Hubble is at an orbital deviation of 28.5 degrees from the equator. This orbital deviation is the same as the latitude of Hubble’s launch site, Cape Canaveral in Florida, and was the easiest and most economical orbit to launch the telescope.

It is not possible to watch the passage of the Hubble telescope from the sky in Iran; But if you want to see where the Hubble telescope is above the earth at this very moment, you can visit the website uphere.space, which provides a real-time image report of Hubble’s movement in orbit. It is also possible to watch the passage of other satellites on this website.

Undoubtedly, the most iconic image captured by Hubble to date is the “Pillars of Creation” taken in 1995. These giant towers consisting of interstellar gases and cosmic particles are located at a distance of 7,000 light years from Earth in the Eagle Nebula.

The reason for choosing the name of the pillars of creation is that a very powerful force of gravity causes these gases and particles to condense and turn them into masses of mass and form a new star system. In fact, the solar system was probably born billions of years ago in the same way. When we look at this picture, it is as if we are looking at the distant past of the earth.

The image above is the same columns of creation recorded with infrared light and as a result, dust and gases can be seen inside. The website space.com has selected the Pillars of Creation as one of the top ten images taken by Hubble.

Hubble’s Deep Field is a stunning image of a section of the Ursa Major constellation that changed the science of astronomy forever. This image, taken in 1995, is as wide as a grain of salt; But it has 3 thousand galaxies in its heart. This image is composed of 342 separate pieces obtained by Hubble’s Deep Wide Astronomical Camera 2 during ten consecutive days.

In this incredibly beautiful image, we are watching the birth of half a million young stars in the middle of a cloud of gas and cosmic particles in the Tarantula Nebula, which is located in the constellation of the Golden Fish at a distance of 160 thousand light years from us; But this nebula is not in the Milky Way galaxy but in the Large Magellanic Cloud galaxy.

The Tarantula Nebula is the brightest non-stellar object ever discovered, and if the Orion Nebula were in the Milky Way, its shadow would fall on Earth.

Saturn has 82 moons, But the passage of the moons over this planet can be seen only when the tilt of Saturn’s rings reaches the point where they look edged, and this event happens once every 14-15 years. This image was captured by Hubble’s Deep Wide Astronomical Camera 2 on February 24, 2009.

The Crab Nebula is located about 6,500 light-years from Earth in the constellation Taurus and is the only survivor of the supernova explosion that Chinese astronomers observed in 1054 AD. This image is obtained in several wavelengths and from the data of three telescopes, the yellow light belongs to Hubble.

The Whirlpool Galaxy or NGC 5194 is an interacting and spiral galaxy located 31 million light-years from Earth in the constellation of the Hounds. This galaxy and its companion, NGC 5195, are easily visible to amateur astronomers and can also be seen with spotting scopes.

The planetary nebula IC 418, known as the Spirograph (due to its apparent resemblance to Euclid’s magic circle), is located about 2,000 light-years from Earth in the constellation Wolf, near the constellation Orion.

The IC 418 nebula was a Sun-like star a few million years ago and became a red giant a few thousand years ago. With the end of the nuclear fuel of this star, its outer shell was ejected and a planetary nebula was formed. In the center of this image, you can see the white dwarf.

Earth comes between Mars and the Sun about once every two years, causing the red planet to glow spectacularly. Hubble recorded this event, called a collision, in 2001.

How does the Hubble telescope work?

The Hubble telescope, 13.2 meters long and currently weighing 12,200 kg, provides its energy with the help of two 7.62 meter panels from the sun and stores it in 6 nickel-hydrogen batteries with a capacity equal to approximately 22 car batteries. saves This telescope is made up of various instruments, each of which is responsible for recording the highest-quality galactic images.

As the telescope orbits the Earth, its Fine Guidance Sensors lock onto the stars. These sensors are part of the pointing control system and guide the Hubble in the right direction. Hubble can lock onto a target a mile away without moving more than the width of a human hair.

After detecting the target, Hubble’s main mirror begins to collect light. This mirror can collect about 40 thousand times more light than the human eye. Light is reflected from the primary mirror to the secondary mirror. The secondary mirror then refocuses the light through a hole in the primary mirror. From there, light shines on Hubble’s scientific instruments.

Hubble has five scientific instruments, including cameras and spectrographs, each with a different way of reading light. Spectroscopy is a tool that divides light into separate wavelengths.

Hubble’s main camera is called Wide Field Camera 3. The camera studies everything in the universe, from the formation of distant galaxies to the planets of the solar system, and can observe three different types of light: near ultraviolet, visible light, and near-infrared. While the human eye can only detect visible light, the Hubble camera can also observe and record near-ultraviolet and near-infrared. Of course, Hubble can only record one type of light at a time.

The Advanced Camera for Surveys takes pictures of large areas in space and has a very high resolution, quantum efficiency, and powerful emulsion filters. This camera increased the resolution of Hubble’s images by 10 times and showed scientists parts of the universe that had never been seen before.

Hubble’s Cosmic Origins Spectrograph reads ultraviolet light. This spectrograph studies the formation and evolution of galaxies, stars, and planets.

Somewhat like a prism, the Space Telescope Imaging Spectrograph breaks down the light that reaches the telescope from celestial objects into its constituent colors, helping scientists determine the temperature, chemical composition, density, and motion of objects in space. determine This spectrograph is also used to detect black holes.

The Near-Infrared Camera and Spectrograph (NICMOS) can sense the heat emitted from distant objects and observe them and spectrograph multiple targets simultaneously. The sensitivity of this camera to infrared waves has made it very efficient for seeing obscure celestial objects such as gases and interstellar dust, as well as for seeing the deepest parts of the universe.

Hubble sends about 150 gigabytes of scientific data to Earth every week. This amount of data is equal to about 45 two-hour movies with HD quality or about 30 thousand mp3 songs. Digital signals are transmitted from Hubble to satellites, then to a ground station, from there to NASA’s Goddard Space Flight Center, and finally to the Space Telescope Science Institute. This institute transforms data into images and information that we can understand.

Hubble’s digital cameras can only take black and white photos; For this reason, astronomers put the recorded image of the object in several exposure modes to record different wavelengths of light using several filters, which are usually red, blue, and green. These images are then superimposed to create a monochrome image. Because Hubble can see in the ultraviolet and infrared ranges, scientists sometimes add extra color to the images to bring out details that are normally invisible to the human eye.

The Hubble telescope is so powerful that it can detect the light of a firefly at a distance of about 11,000 kilometers, and scientists have used this amazing ability to understand many mysteries of the universe. For example, astronomers’ estimates of the age of the universe in the past differed greatly; But Hubble’s observations of old, burned-out stars helped them narrow down the Big Bang to about 13.7 billion years ago.

This telescope was also able to find early signs of supermassive black holes at the center of neighboring galaxies with the help of its high zoom power. The role of this telescope has been very vital in discovering exoplanets that may have suitable conditions for life. Perhaps Hubble’s most important discovery from the study of supernovae was the formation of the theory that a mysterious force known as “dark energy” may be the reason for the acceleration of the universe’s expansion, and this discovery would not have been possible without Hubble’s powerful lenses.

As Hubblesite explains, people often mistakenly think that the power of a telescope depends on its ability to magnify objects; But the fact is that the power of telescopes lies in gathering more light than the human eye can absorb, and the greater the ability of the telescope to gather light, in other words, the larger the surface of the telescope’s mirrors, the greater its power. The Hubble telescope also does this using a technique that was first presented 340 years ago; A technique called Cassegrain reflector, which consists of two convex and concave mirrors. The large, convex primary mirror absorbs light (Hubble’s primary mirror is 2.4 meters in diameter) and reflects it back to a smaller, concave secondary mirror (0.3 meters in diameter on Hubble). The light is then reflected through a hole in the middle of the primary mirror onto the sensors of the Hubble instrument.

Thanks to its large and powerful mirrors, Hubble can look deep into space; But only by looking at the NASA images, you can’t understand the incredible zoom power of this telescope. For this reason, astronomers have published a large number of images recorded by Hubble at different distances in the form of a video that shows off the power of Hubble’s mirrors in the best possible way.

On April 24, 1990, corresponding to May 4, 1369, the space shuttle Discovery took off from the earth with its very valuable cargo, the Hubble telescope. The next day, April 25, a team of astronomers put this telescope into space and Hubble’s exploratory journey began. On that historic day, no one could have predicted the wonders that Hubble was going to observe and record in the next 31 years.

In the same way, April 24th is Hubble’s birthday, and every year on this day, NASA publishes a beautiful and new image recorded by Hubble. Last year, on the occasion of the end of three decades of the Hubble mission in space, NASA published a new and amazing image of two nebulae in the Large Magellanic Cloud, which is a small galaxy at a distance of 163 thousand light years from the Milky Way.

The larger, red nebula is called NGC 2014, and the bright, newly formed stars at its heart are 10 to 20 times the size of the Sun. The blue nebula known as NGC 2020 was formed when a star 200,000 times larger than the Sun ejected a large amount of gas. To the eyes of the researchers, this recorded image resembled a rock or a coral reef; That’s why they named it “Cosmic Reef”.

The Hubble telescope explores the world 24 hours a day, seven days a week. That means the telescope has observed and recorded cosmic wonders every day of the year, including your birthday. To find out what image Hubble recorded on your birthday, you can go to this page on the NASA website and enter your birthday month and day in Gregorian.

Because of its position in space and its advanced lenses, the Hubble telescope can look at the most distant places that are hidden from the view of telescopes based on the Earth. Since it takes a long time for light to travel long distances, Hubble’s amazing capabilities make it a kind of time machine. The light that Hubble observes from distant objects only shows what the object looked like when the light left it, not what it looks like today; So when we look at the Andromeda Galaxy, which is 2.5 million light-years away from Earth, we see it as it was 2.5 million years ago; It is as if we are looking very far into the past.

Therefore, with Hubble, you can observe very distant cosmic objects that would never be visible without this telescope. For example, in 1995, when astronomers pointed the Hubble telescope at a seemingly empty region in the constellation Ursa Major, not expecting the telescope to capture an image of this region, to their disbelief, after 10 days, images of more than 3,000 observed the galaxy. This image was later named “Hubble Deep Field” (Hubble Deep Field), which you saw in the Hubble Telescope Images section.

Some of the galaxies recorded in the Hubble Deep Field were so young that they had not yet begun to form stars in earnest. A little later, other background observations were made in the same area, each time looking deeper into space. The “Hubble Ultra-Deep Field” image, which was released in 2004 and has four times the resolution of the Hubble Deep Field, is the deepest and most distant point in the universe that the human eye has seen. The galaxies recorded in this image are about 13 billion light years away from us; That is when the universe had spent only 5% of its current life.

By observing the early universe, Hubble helped astronomers calculate the time since the Big Bang, thus estimating the age of the universe in the range of 13.7 billion years. This telescope also examines stars separately in different stages of their evolution; From the clouds of cosmic particles that form newborn stars to the remnants of stars that exploded long ago and those that are at the limit of the distance between these two stages. Hubble has been able to look into the Milky Way, neighboring galaxies, the Magellanic Clouds, and the Andromeda Galaxy.

But more challenging than observing stars is observing planets that orbit other suns outside the solar system. However, in 2008, Hubble captured images of Fomalhaut b, the first time an extrasolar planet had been directly imaged in visible light. Most planets are very difficult to photograph. Most recorded images of planets have been obtained by detecting their atmospheres as they pass in front of their sun; In this way, the atmosphere of these planets filters the light of the stars and Hubble records these changes.

Hubble may spend most of its time looking at objects that are light-years away from Earth, But sometimes it also takes pictures of the planets that revolve around our sun. The images recorded by Hubble of Jupiter, Saturn, and even Pluto are of such clarity and detail that only probes orbiting these planets can capture them better. Hubble images allow scientists on Earth to observe changes in the atmosphere and surface of these planets. When Comet Shoemaker-Levy 9 collided with Jupiter in 1994, Hubble recorded the fatal collision. In fact, this event was the first direct observation of an extraterrestrial collision in the solar system and received extensive media coverage. After this collision, a lot of information about the atmosphere of this gas giant was revealed.

Additionally, in 2014 and 2016, Hubble was able to observe geysers erupting from the icy surface of the moon Europa (one of Jupiter’s 69 moons), thus making it one of the important targets in the search for habitable worlds far from Earth.

With more than three decades in orbit, Hubble has provided scientists with a better understanding of planets, galaxies, and the entire universe. Among the most amazing discoveries and research projects of Hubble, the following can be mentioned:

• Creating a 3D map of dark matter
• Discovery of two moons of Pluto named Nix and Hydra
• Help determine the rate of expansion of the universe
• The discovery that almost all massive galaxies are held firmly in place by a black hole
• Help to more accurately calculate the age of the world

Hubble will be 31 years old in 2021. Engineers have designed Hubble so that it can be repaired and upgraded if necessary. Since Hubble’s launch, five space shuttle missions have taken astronauts near the telescope to repair and upgrade it. The last Hubble upgrade mission was in 2009. This telescope will no longer be repaired or upgraded, But it will continue to perform missions in space.

Meanwhile, NASA and its international partners are preparing the $9 billion James Webb Space Telescope. Named in honor of the NASA administrator (1968-1961) who played an important role in the Apollo space program, James Webb, this telescope is an infrared type that is larger than Hubble and capable of seeing inside clouds and particles in space. This telescope will not need repairs during its 6 to 10-year life. Instead of orbiting the Earth, the Webb Telescope will orbit the Sun at a distance of one million miles from the Earth, and therefore will be able to look much deeper into space, and the light that traveled only a few hundred million years after the Big Bang. had started to observe.

Although the launch of the James Webb Telescope has been regularly delayed, it is currently scheduled to launch in November 2021 (Aban 1400). Astronomers hope to have both telescopes in space at the same time before Hubble retires.

Read more: Involvement of the James Webb Space Telescope in a mission beyond its capacity