After the discovery of Uranus, astronomers for decades believed that it was the "extreme" planet of the solar system. The movement of Uranus was monitored through telescopes from year to year and, based on these observations, the position of the planet was calculated for many years to come. But it turned out that the calculations did not coincide with the observations. The attraction of all the other planets was taken into account, but there were still some unforeseen perturbations in the motion of Uranus.
And then astronomers suggested that this irregularity in the movement of Uranus must have depended on some other planet orbiting the Sun at an even greater distance from it. The task arose: by the perturbation that the unknown planet produces, to find its position in space. Scientists D. Adams in England and W. Le Verrier in France independently solved this problem. The orbit of the eighth planet was calculated, its coordinates were determined for a certain moment of time, and on September 23, 1846, astronomer I. Galle discovered a planet in the indicated place, which was not on the star map. The eighth planet of the solar system was named Neptune in honor of the god of the seas in Roman mythology. The discovery of this planet was a triumph of celestial mechanics, a triumph of the heliocentric system.
Since not all deviations in the movement of Uranus were explained by the influence of the planet Neptune, the search for the source of the perturbing force was continued, and in 1930, using a telescope and studying photographs, an unknown planet was discovered and named Pluto (in Roman mythology, the god of the underworld).
The discovery of the ninth planet in the solar system belongs to the American astronomer Clyde Tombaugh.
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The vegetation of deserts is very peculiar and depends on the type of desert, on the characteristics of the climate and the presence of moisture. First, the vegetation does not form a continuous cover anywhere. Secondly, in the desert there are no forests, no undergrowth, no grass, and, finally, large shrubs have no leaves. Sandy deserts are the richest in herbaceous vegetation. In the gypsum and rocky deserts, shrubs, semi-shrubs and sagebrush predominate….
The Earth's crust - the outer layer of the globe, the surface on which we live - consists of about 20 large and small plates, which are called tectonic. The plates are 60 to 100 kilometers thick and seem to float on the surface of a viscous, paste-like molten substance called magma. The word "magma" is translated from Greek as "dough" or ...
The aurora borealis is one of the most beautiful, grandiose and majestic phenomena of nature. Some people think that it only occurs in the North and call it "Northern Lights". And this is wrong, because it is observed with equal success both in the northern and in the southern polar and circumpolar regions. Here is how the well-known explorer of Severnaya Zemlya figuratively describes it...
Time is constantly flowing, and everything in the world changes with time. The need to measure time in people appeared a very long time ago, everyday life is connected with the change of day and night. In ancient times, the position of the Sun in the sky served as a time indicator for man. By the Sun they were guided both in space and in time. The apparent movement of the Sun across the sky allowed a person to measure almost equal ...
The great Newton was interested in the history of the division of the sky into constellations. He wrote a book about his research, in which he analyzed the works of ancient authors, comparing them with astronomical data. And he received that the division of the celestial sphere into constellations was carried out in connection with the expedition of the Argonauts (Newton was sure that the voyage of the ship Argo from Greece to Colchis was a truly historical event, ...
The first permanent observatory arose in China (XII century BC). It was a tower with a platform at the top, designed to accommodate portable goniometers. Astronomers of ancient China introduced solar and lunar calendars, compiled star catalogs, made a star globe, accurately recorded the appearance of comets, flashes of bright stars. These observations, information about which came from the depths of centuries, ...
Craters are mountainous regions of the lunar surface that have rounded outlines. The sizes of craters are from 1 m to 250 km. Large and medium-sized craters have been known since the first telescopic observations of the Moon. They bear the names of famous scientists: Aristotle, Herodotus, Hipparchus, Copernicus, Kepler, etc. Many large craters are surrounded by gentle ramparts, have a flat bottom, in the middle of which a central hill rises ....
The sun, the only star in our solar system, is structured like many stars. This is a huge massive ball, which is a clot of hot gas. This is a powerful source of radiation of light and heat, inside which hot gases, called plasma, are constantly moving, moving. Scientists, observing the surface of the Sun, investigating all types of solar radiation, using measurements and calculations, have compiled ...
The planet closest to the Sun is Mercury, the smallest of the terrestrial planets. Its diameter is 4880 km, i.e. about 1/3 of the earth's diameter, the mass is 20 times less than the mass of the Earth. Photos of Mercury were obtained in 1974 by the American interplanetary station Mariner-10. They showed the similarity of this planet with the moon. An abundance of small and large craters, sometimes with…
In the XVIII century, the planetary system was studied even before the planet Saturn. Although scientists have assumed that even more distant planets exist, planets such as Uranus, Neptune and Pluto. The famous British astronomer William Herschel in 1781, observing the stars through a telescope, noticed a new luminary, previously unnoticed by the naked eye. After some time of observation, he realized that he had discovered a new planet. The new planet was named Uranus.
Uranus is the seventh planet, slightly less than 2900 million km from the Sun. Uranus revolves around the Sun in 84 Earth years. The rotation speed of Uranus around the Sun is 7 km / s, while the Earth rotates around the Sun at a speed of 30 km / s.
Uranus is a fairly bright planet and if you know exactly where to look, you can see it with the naked eye. It changes its position among the stars and, despite the fact that it does not twinkle, looks like a star. Uranus is the only planet that rotates "lying on its side". It is believed that this position was determined millions of years ago as a result of a collision with a large body.
Uranus is smaller than Saturn but much larger than Earth. The temperature on Uranus is minus 200 degrees and below. There is a small stone core in the center of the planet. The cloudy atmosphere of Uranus is mostly hydrogen-helium, and also contains methane. Due to the presence of a large amount of helium in the upper atmosphere, Uranus has a blue-green color. In 1977, it was discovered that Uranus has rings made of dust. Uranus makes a full rotation around its axis faster than the Earth in 18 hours.
In 1846, German astronomer Johann Gottfried Galle discovered Neptune, the eighth planet in the solar system. He made his discovery by pointing the telescope exactly at the place indicated by the results of their calculations by the French astronomer Le Verrier and the English scientist Adams.
This discovery confirmed the correctness of the Copernican system of the world and Newton's laws of motion and attraction, on which all calculations performed in celestial mechanics are based.
Neptune is more than 4500 million km from the Sun. It completes one revolution around the Sun in 165 Earth years.
The temperature on the surface of Neptune is also less than minus 200 degrees.
Neptune is a planet - a gas giant, but in size it is slightly smaller than Uranus. Neptune completes a complete revolution around its axis in 16 hours. Scientists believe that Neptune is made up of a mixture of water, rocks, liquid ammonia, and methane.
In addition to hydrogen, helium and water, Neptune's thick cloudy atmosphere contains methane gas, thanks to which Neptune has a blue color and is called the "Blue Planet".
Violent storms rage in Neptune's atmosphere. Long thin clouds rush over Neptune. They are driven by such violent winds as are not found on any other planet in the solar system. The wind speed can reach 2000 km/h. Therefore, Neptune is also called the "Planet of Storms".
Neptune is not visible to the naked eye, it can only be seen with binoculars as a small star.
Pluto differs sharply from the giant planets. It was discovered in 1930 by the American astronomer Clyde Timbo. The mass of Pluto is about the same as the mass of the Earth. Of all the planets, Pluto is almost always the farthest from the Sun. It revolves around the Sun in a highly elongated oval orbit. Therefore, the distance of Pluto from the Sun varies greatly: from 4425 to 7375 million km. Out of every 249 years, only 20 years Pluto is closer to the Sun than Neptune.
Pluto's diameter is about 2300 km. Even in the most powerful ground-based telescopes, Pluto looks like a star. It is not yet possible to examine its surface. Judging by the photographs, the surface of Pluto is covered with frozen methane and nitrogen. Perhaps there is a thin layer of the atmosphere.
Planet cycles Uranus, Neptune and Pluto long, and in astrology it is believed that they affect entire generations of people, animals and the growth of perennial plants: trees and shrubs. A person born in one of the cycles of these planets is quite likely to become a genius.
Uranus was named after the ancient Roman god of heaven. In astrology, Uranus is considered the planet of the future, unexpected events, unusual phenomena. He patronizes everything new, original thoughts and inventions, the human genius that creates these inventions, new opportunities for new discoveries.
Uranus affects our creative individuality and personal "I", the desire for friendship, freedom and independence. Uranus directs entire teams in creativity.
The planet Neptune is associated in astrology with the oceans. Neptune in mythology is the God of the seas and oceans. He governs all expanses of water, as well as all processes and phenomena hidden under water. Neptune influences the weather by adjusting the amount of precipitation as it sees fit.
Astrologers believe that Neptune affects heredity, the world of the subconscious, imagination, and the spiritual component of the personality.
Pluto got its name in honor of the ancient Roman god of the underworld and the souls of dead people.
In astrology, Pluto symbolizes death and rebirth. It is also believed that Pluto communicates with the World Mind.
Pluto has a powerful impact on generations, exerting an extreme impact on collectives, communities and individuals, exciting an explosion of uncontrollable energy in them. Pluto promotes destructive processes, but always after that creates the conditions for a new revival.
Discovery of Uranus, Neptune and Pluto
Uranus and Neptune on the celestial sphere
Uranus . The third largest planet in the solar system, Uranus is visible from Earth as a 6th magnitude star. Since 1690, astronomers have shown it as a star on their charts several times. However, it was discovered as a planet only almost two centuries after the invention of the telescope, by the musician and amateur astronomer William Herschel.
Herschel was a native of Germany, at the age of 19, escaping from recruitment in the army, he emigrated to England. After many hardships and hardships, he rose to prominence as a performing musician, composer and music teacher in the seaside resort town of Bath near Bristol. In addition to music, Herschel's passion was astronomy.
Disappointed in a small reflector acquired in 1773 with a focal length of 2.5 feet, he made with his own hands a reflector almost 2 meters long and a main mirror 20 cm in diameter. And with the help of his new instrument, he began in 1775 a survey of the entire sky visible from Bath. Between music lessons, Herschel polished metal mirrors for telescopes, gave concerts in the evenings, and spent his nights observing the stars.
Herschel telescope
Having completed the survey of the entire sky, Herschel decided to repeat it. On March 13, 1781, he studied the location of the stars in the region of the constellation Taurus. One of the stars within this area seemed strange to him - instead of a bright point, it looked like a small disk, so he made the following entry in his observation diary: "of an unusual appearance - either a star surrounded by a nebula, or a comet." Herschel believed he had discovered a new comet and sent a letter to the Royal Society. After 2 months, Academician Andrei Leksel of St. Petersburg calculated the parameters of the orbit of this celestial body, which showed that it revolves around the Sun in a circle whose radius is 19 times greater than the radius of the Earth's orbit. The resulting orbit looked more like a planet than a comet. It became clear that for the first time since the Babylonian priests a new planet had been discovered in the solar system.
William Herschel
Herschel suggested that the newly discovered celestial body be called the planet George in honor of King George III, who ruled at that time in England. However, this name did not take root, and another name became generally accepted - Uranus, proposed in the year of the discovery of the planet by the German astronomer Johann Bode, who believed that it was necessary to continue the historical tradition of planet names from ancient Roman mythology in the outer parts of the solar system. Thanks to the discovery of Uranus, William Herschel was able to become a professional astronomer, and then the largest observing astronomer in history. In the same year that Uranus was discovered, Herschel was elected a Fellow of the Royal Society of London and received a doctorate from Oxford University.
Six years later, in 1787, Herschel discovered the two largest satellites of Uranus Oberon and Titania - objects of 13-14 magnitude. Two more satellites were found in 1851 by the prosperous Liverpool brewer William Lassell, an eminent British amateur astronomer of the Victorian era. Finally, in 1948, American astronomer Gerard Kuiper found the smallest of the five main moons, Miranda.
The first four satellites did not get their names from the discoverers. Names were given to them in the 19th century by the son of William Herschel, John Herschel, who himself was one of the most prominent astronomers in the world. In violation of the astronomical tradition, which requires taking names for planets and satellites from the mythological plots of different peoples, the satellites received the names of characters from the works of English writers - Shakespeare and Pope. The brightest among the satellites of Uranus - Ariel received the name of the kind, bright spirit of the air - a character found both in Shakespeare's play "The Tempest" and in Pop's poem "The Kidnapping of the Lock". The satellite next to him - Umbriel, twice as dark, was named after an evil, dark spirit from the same poem by Pop. The two largest of Uranus' moons, Titania and Oberon, were named after the queen of the fairies and her husband, the king of good spirits from Shakespeare's A Midsummer Night's Dream.
Uranus and its moons
When a new chemical element was discovered in 1789, which turned out to be the heaviest element known at that time, it was named "uranium" in honor of the discovered planet. Only a century and a half after the discovery of this element, it became a key element in nuclear physics and technology. When new elements with atomic numbers 93 and 94, at that time the last in the periodic table, were obtained from uranium (atomic number 92) in the 20th century, they were named after the planets following uranium: neptunium (after the planet Neptune) and plutonium (after the planet Pluto).
Neptune . Soon after the discovery of Uranus in 1781 by W. Herschel, incomprehensible anomalies began to be revealed in the movement of this planet - it either “lagged behind” the calculated position, then it was ahead of it. Russian astronomer Academician Andrei Leksel, who proved that the object discovered by Herschel is a planet, drew attention to the anomalies in the motion of Uranus back in 1783. After studying the features of the planet's motion, Leksel suggested that Uranus is affected by the attraction of an unknown cosmic body, whose orbit is located even further from the Sun.
In 1821, the French astronomer Alexis Bouvard published tables of the position of Uranus for many years to come. But over the next 10 years, the data from direct observations of Uranus increasingly diverged from Bouvard's tables, which caused the scientific community to explain this phenomenon.
This question was of great interest to the 22-year-old student of Cambridge College, John Adams (1819-1892). And he suggested that some invisible and not yet known planet, located beyond Uranus, is to blame for this. The fact that it could influence the movement of Uranus followed from Newton's law of universal gravitation.
Fascinated by this problem, Adams decided to calculate the orbit of an unknown planet from the deviations of Uranus, determine its mass and indicate its location in the sky. Thus, for the first time in the history of astronomy, man set himself the most difficult task: using Newton's law and the methods of higher mathematics, to discover a new planet in the solar system.
The task was much more difficult than it seemed at first glance. The difficulties were aggravated by the fact that in those days not only were there no computers, but there were also not enough auxiliary mathematical tables. For 16 months, Adams was busy calculating the orbit of an unknown planet. Finally, having completed his painstaking work, he indicated the place in the constellation of Aquarius where the planet was supposed to be on October 1, 1845.
Adams wanted to report the results of his calculations to the Royal Astronomer George Erie (1801-1892). But, to his chagrin, the meeting with Eri, on which he placed so many hopes, did not take place. Instead of a detailed report, I had to confine myself to a short note. When Eri read it, he had doubts. Meanwhile, the results of the calculations were extremely accurate: the unknown planet was only 2 degrees from the place indicated by Adams. And if astronomers had wished then to search for it, the planet would not have gone unnoticed. But Adams's work lay in the Astronomer Royal's desk, and no one knew about it.
In parallel with this summer of 1845, F. Arago, director of the Paris Observatory and head of French astronomy at that time, suggested that W. Le Verrier take up the "problem of Uranus." At this time neither he nor Arago they did not know that Adams had been working on it for two years in England, and that he had already received significant results.
In November 1845 Le Verrier published the first article on Uranus. He rebuilt the entire theory of the motion of Uranus, taking into account perturbations from known planets, refining everything that had been done by Bouvard. His work and the nature of the presentation itself were distinguished by thoroughness, taking into account the finest details, and clarity. The perturbations of Uranus' orbit were calculated by two different methods, which ensured that there were no errors. Finally, the accuracy of the calculated coordinates of Uranus was 0,1.
It turned out that Adams and Le Verrier, not knowing anything about each other, began a mathematical search for an unknown planet almost simultaneously. In the summer of 1846, Le Verrier made a report at the French Academy of Sciences on the results of studying the deviations of Uranus. He proved that the cause of these deviations is not Jupiter or Saturn, but an unknown planet located beyond Uranus. But the most interesting thing was that in terms of the position of the new planet in the sky, Le Verrier's calculations almost completely coincided with those of Adams.
It was only now that George Erie realized that he had mistrusted Adams's work in vain. And he asked the Cambridge University Observatory to examine a section of the starry sky in the constellation Aquarius, where, according to mathematical calculations, an unknown planet should have “hidden”.
Neptune in the constellation Aquarius
Unfortunately, neither England nor France yet had a detailed star map of the studied area of the sky, and this made it very difficult to search for a distant planet.
Then Le Verrier wrote a letter to the Berlin Observatory to Johann Galle (1812-1910) with a request to immediately start searching for a transuranic planet.
Galle, who had the right star map, decided not to waste time. On the same night - September 23, 1846 - he began to observe. The search lasted about half an hour. Finally, Galle saw a faint star, which was not on the map. At high magnification, it appeared as a small disk. The next night Galle continued his observations. During the day, the mysterious object moved noticeably among the stars. Now there was no doubt: yes, it was she - a new planet!
The discovery of Neptune was extremely important, because it finally confirmed the validity of the heliocentric system of the world of Nicolaus Copernicus. At the same time, the validity and universality of the law of universal gravitation was proved.
Pluto . Taking into account the influence of Neptune on Uranus made it possible to reduce the discrepancies between the theoretical and observed motion of Uranus by dozens of times, but full accuracy was not achieved. In 1848, the American astronomer B. Pierce suggested the existence of a ninth planet. In 1874, S. N'kom built a new theory of the motion of Uranus, taking into account perturbations from Jupiter, Saturn and Neptune. He also assumed the existence transneptunian planets.
First started searching transneptunian(ninth) planet famous American astronomer Percival Lovell (1855-1916). Having carefully studied its possible influence on the motion of Uranus, he calculated the orbit of the proposed planet, determined its mass and conventionally called it Planet X.
“The ninth planet,” Lovell wrote, “is located at 6 billion km from the Sun, and it takes 282 years to complete one revolution around the Sun. Lovell believed that this is a relatively small planet, which is visible from Earth as faint telescopic star. Judging by the results of the calculations, the planet was "hiding" in the zodiac constellation Gemini.
At the beginning of 1905, Lovell, using a 5-inch astrograph (a special telescope equipped with a photographic camera), began photographing sections of the starry sky in Gemini. He exposed each plate for three hours and then developed it. The plates produced images of stars, including stars of the 16th magnitude. The brightness of such stars is 10 thousand times weaker than the brightness of the faintest stars visible to the naked eye. After several nights, the astronomer made repeated photographs of the same parts of the starry sky.
Then came the most important stage of research. The negatives, on which the same sections of the sky were photographed, were carefully superimposed on each other by Lovell so that the images of the stars coincided. He carefully examined each pair of combined negatives through a magnifying glass.
Searches in the last years of his life greatly weakened the health of the astronomer, he died in 1916.
Ironically, 15 years later, in Lovell's photographs taken in 1914-1915, "planet X" was nevertheless discovered. An astronomer, looking for an object with a magnitude of 12-13 magnitudes, simply did not pay attention to a star of 15 magnitudes.
After that, the interest of astronomers in the search for the ninth planet began to fall. Only at the Lovell Observatory were further searches planned. In the late 1920s, Lovell's brother, Abbot Lawrence, made an additional financial contribution to the observatory's fund. Part of this money went to a new wide-angle 32.5 cm telescope capable of photographing stars up to magnitude 17 in an area of 160 square degrees within an hour, i.e. 1/260 of the entire visible sky. The new chamber began work on April 1, 1929.
A young employee of the observatory Clyde William Tombaugh (1906-1997) took an active part in the work on the telescope. In early April 1929, Clyde Tombaugh, using a 13-inch astrograph, began photographing the stars in the constellation Gemini, where, according to Lovell's calculations, the planet X should be located. Every clear night he photographed a certain section of the starry sky, and two or three nights later he received a second plate with an image of the same section. To ensure that nothing went unnoticed, Clyde applied an almost flawless search technique: he photographed all parts of the starry sky three times.
Clyde Tombaugh
Hundreds of thousands, no, millions of stars have already been captured! And in this stellar ocean it was necessary to find a barely noticeable planet. To do this, Clyde compared paired negatives on a special device - blink microscope. The device was designed in such a way that it allowed one to view two plates in turn, on which the same section of the starry sky was photographed. If a moving object was photographed on the plates, then with a quick change of images, it seemed to jump from one place to another, while "fixed" stars do not experience displacements. Thanks to this method (the “blinking” method), Tombo hoped to find a small point, lost among millions of stars, the planet X.
Clyde is completely gone in search. With his characteristic energy, he worked 14 hours a day: at night he photographed the starry sky, and during the day he compared the plates, carefully examining each “suspicious” image. Images of millions of stars have already been viewed. New asteroids, variable stars, galaxies discovered... And no sign of Planet X! When will he finally find her? Or is he really wasting his time? But Clyde every time drove away doubts and with even greater perseverance began to search.
February 18, 1930 Clyde Tombaugh, as always, examined the next pair of records, filmed in the last decade of January. Suddenly, near the star of the Gemini delta, one of the weak points jumped. He had already observed shifts of asteroids more than once, but this shift was not like all the previous ones - it was very small. Judging by the magnitude of the shift, the unknown object was very far from the Earth and from the Sun. Clyde's heart began to beat violently, and he shouted, “Here she is! It must be Planet X!”
More than 100,000 alleged images of the planet were in fact photographic defects, and each such "marriage" had to be rechecked on the third picture. Finally, in the photographs of the vicinity of the star Delta Gemini, taken on January 21, 23, 29, 1930, Tombo discovered a slowly moving "star-like" object. Subsequent observations confirmed that it was not a comet or an asteroid. On March 13, the director of the Lovell Observatory, V. M. Slifer, announced the discovery of a new planet. This news immediately spread on the radio all over the world.
Discovery of Pluto
Even through a large telescope, the object discovered by Tombo looked like a faint 15th-magnitude star with no sign of a planetary disk. And to make sure it's real transneptunian planet, astronomers began to closely monitor its movement. Several weeks have passed. Observations have shown that it moves exactly as it should be for a planet beyond Neptune to move.
March 13, 1930, on the day of the 75th anniversary of the birth of Lovell, who initiated the search for Planet X, the world learned about its discovery.
The discovery of Pluto was a new triumph of scientific foresight. The boundaries of the planetary system were moved away from the Sun immediately by 1.5 billion km!
Pluto and its moons (photo from the Hubble Space Telescope)
Many thought the planet should be named Lovell, but in the end, the Lovell Observatory settled on the name Pluto, proposed by the 11-year-old daughter of Oxford astronomy professor Venesha Burney. According to Greco-Roman mythology, Pluto (Hades) was the ruler of a dark underworld kingdom, and it was quite appropriate to assign his name to a planet from the kingdom of darkness on the periphery of the solar system. The name took on a new symbolic meaning when, in 1945, the chemical element plutonium, named after the newly discovered planet, became the basis for the first atomic bombs.
Possible view of Pluto's surface
For 76 years after its discovery, Pluto was considered the ninth planet in the solar system. On the edge XX and XXI centuries beyond the orbit of Pluto, many other planets were discovered, some of which turned out to be even larger than Pluto in size. In this regard, at the congress of the International Astronomical Union in 2006, Pluto was recognized as one of the objects of the Kuiper belt and received the status of a "dwarf planet".
Questions and tasks
1. How were Uranus, Neptune and Pluto discovered? Name their discoverers. Where did their names come from?
2. Where did the name of the chemical elements come from - uranium, neptunium, plutonium?
3. Why was it possible to discover Uranus only in XVIIIcentury, although it can be seen with the naked eye?
4. Why is the discovery of Neptune considered the final confirmation of the Copernican heliocentric system?
5. What was the main difficulty in finding Pluto?
Until the beginning of the twentieth century, 8 planets of the solar system were known. The last 8th planet was called Neptune. Scientists have a question - is this really all, is there really nothing more beyond Neptune. I did not want to believe it, although scientists did not have any data on the presence of at least some celestial bodies beyond the orbit of Neptune. In the 20s of the twentieth century, a group was created in the United States, which was given the daunting task of finding the mythical planet “X” beyond the orbit of Neptune, which haunted not only scientists, but also astronomy lovers. In the late 1920s, the most talented scientist, 23-year-old Clyde Tombaugh, was accepted into the group. Clyde was fond of astronomy as a child and, to the happiness of all of us, made this science his profession. He began his exploration of outer space by making a real telescope in the yard of his house without anyone's help. He collected it from what lay badly in his yard and in the barn. For example, he borrowed a flywheel for adjusting the tilt angle of the telescope from a tractor, a pipe from a mechanism by which grain enters the elevator, etc.
Later, being a recognized scientist, he called his first telescope his most ingenious invention.
Tombo, one of the first to guess how you can find the planet "X". To do this, you need to periodically take pictures of the same sections of the starry sky, and if a new moving point is found there (the stars, as you know, are stationary), then we can assume that a new space object has been discovered, but for this it is necessary to exclude all known at that time planets and other space objects: comets, asteroids, etc. The task seems completely impossible, given that planets, unlike stars, do not shine, but only reflect sunlight.
Considering that planet X is so far from the Sun that there is practically no light there, it seemed completely impossible to see it with the telescopes that existed at that time. Let's not forget that at that time there were no modern technologies, digital cameras, computers and telescopes launched into the Earth's orbit, where the Earth's atmosphere did not interfere with taking high-quality pictures.
And yet, in 1930, Clyde Tombaugh managed to find such a point - it was the first planet discovered by an American. The message about the discovery of the new 9th planet of the solar system and its picture taken by K. Tombo instantly circled the whole world.
The name of the new planet came up with 11-year-old American schoolgirl Venice Burney. She suggested naming it Pluto, after the ancient Greek god of the underworld. Everyone liked this option. That's what they called it. Interestingly, the names of the satellites of Mars: Phobos and Deimos were suggested by her great-uncle.
So the discovery of Pluto, the ninth planet of the solar system, was made.
Scientists decided that with the discovery of Pluto in the solar system, everything had been studied and there was nothing more to look for, but, as it turned out, everything was just beginning.
SEARCH AND DISCOVERY OF THE NINTH PLANETBorislav Slavolubov
On March 13, 1783, William Herschel discovered the planet Uranus. This immediately doubled the size of the solar system. According to the observations of the planet, its orbit was determined and the theory of the motion of Uranus was constructed. However, the observed motion of Uranus systematically differed from that predicted. This discrepancy allowed John Adams and Urbain Le Verrier to theoretically predict the existence of an eighth planet, Neptune, discovered by Johann Galle on September 23, 1846. The discovery of Neptune was a real triumph for Newton's theory of universal gravitation.
Taking into account the influence of Neptune on Uranus made it possible to reduce the discrepancies between the theoretical and observed motion of Uranus by dozens of times, but it was not possible to achieve full accuracy. In 1848, the American astronomer B. Pierce suggested the existence of a ninth planet. In 1874, S. N'kom built a new theory of the motion of Uranus, taking into account perturbations from Jupiter, Saturn and Neptune. He also suggested the existence of a trans-Neptunian planet.
The search for an unknown planet began at the end of the 19th century, the astronomer Percival Lovell (1855-1916). In 1896 he specified the errors in the motion of Uranus. And, based on his calculations, he suggested that the ninth planet has a period of revolution of 282 years and a brightness of 12-13 magnitudes. In 1905, Lovell began a practical search, photographing the sky with a 5-inch telescope. To do this, he photographed the same area of the sky with a period of several days, and compared the resulting images, superimposing them on top of each other. Finding nothing, Lovell in 1908 began to study the motion of Neptune. One of the most likely constellations for finding "planet X" he considered the constellation Gemini. Searches in the last years of his life greatly weakened the health of the astronomer, he died in 1916.
Ironically, 15 years later, in Lovell's photographs taken in 1914-1915, "planet X" was nevertheless discovered. An astronomer, looking for an object with a magnitude of 12-13 magnitudes, simply did not pay attention to a star of 15 magnitudes.
In 1919, Lovell's colleague at the Harvard Observatory, Henry Pickering, repeated Lovell's calculations, using data from the trajectories of two planets at once - Uranus and Neptune. He also pointed to the constellation Gemini as the place to look for the ninth planet. At Pickering's request, astronomer Milton Humason of the Mount Wilson Observatory began photographing the constellation. Humason did photograph "planet X" on two of his plates, but he was also unlucky and did not notice it. On one, the image of the planet was damaged by a defect on the plate, and on the other, the image of a bright neighboring star obscured it. Some time later, Humason abandoned the search.
After that, the interest of astronomers in the search for the ninth planet began to fall. Only at the Lovell Observatory were further searches planned. In the late 1920s, Lovell's brother, Abbot Lawrence, made an additional financial contribution to the observatory's fund. Part of this money went to a new wide-angle 32.5 cm telescope capable of photographing stars up to magnitude 17 in an area of 160 square degrees within an hour, i.e. 1/260 of the entire visible sky. The new chamber began work on April 1, 1929.A young employee of the observatory Clyde William Tombaugh (1906-1997) took an active part in the work on the telescope. The survey, beginning with the constellation Aquarius, moved month after month through the constellations of Pisces, Aries, and Taurus, reaching Gemini in early 1930. The interval between 3 shots was two or more days, depending on the weather. During the shooting, Tombo looked at millions of stars in a comparator blank - an instrument equipped with a double microscope that allows the observer to alternately see the same region of the sky on two plates. When viewed through a comparator blank, any object that has moved across the sky between two exposures appears to be jumping back and forth, while the stars appear stationary.
More than 100,000 alleged images of the planet were in fact photographic defects, and each such "marriage" had to be rechecked on the third picture. Finally, in the photographs of the vicinity of the star Delta Gemini, taken on January 21, 23, 29, 1930, Tombo discovered a slowly moving "star-like" object. Subsequent observations confirmed that it was not a comet or an asteroid. On March 13, the director of the Lovell Observatory, V. M. Slifer, announced the discovery of a new planet. This news immediately spread on the radio all over the world.
Many thought the planet should be named Lovell, but in the end, the Lovell Observatory settled on the name Pluto, proposed by the 11-year-old daughter of Oxford astronomy professor Venesha Burney. According to Greco-Roman mythology, Pluto (Hades) was the ruler of a dark underworld kingdom, and it was quite appropriate to assign his name to a planet from the kingdom of darkness on the periphery of the solar system.
The discovery of Pluto in old photographs from 1914 made it possible to quickly plot the planet's orbit. Even in the most powerful telescopes of the time, no details were visible on Pluto. For a long time it was believed that the size and mass of the planet are close to the earth or, in extreme cases, to Mars. However, in 1950, J. Kuiper, using the 5-meter telescope of the Palomar Observatory, estimated the angular diameter of Pluto at 0.23 arc seconds. This corresponds to a diameter of 5900 km. After some time, an even more radical limit on the size of Pluto was obtained. On the night of April 28-29, 1965, Pluto's occultation of a 15th-magnitude star was supposed to occur, but none of the 12 observatories observing the occultation even a partial occultation was recorded. This meant that the diameter of Pluto does not exceed 5500 km.
Independent estimates of Pluto's mass have been made. The American astronomers R. Duncomb, P. Seidelman, E. Jackson and the Polish astronomer V. Klepchinsky did a great job of processing 5426 observations of the positions of Neptune for 1846-1968 and, taking into account the perturbations from all other planets, obtained the best agreement between the theory and observations in the case if the mass of Pluto is 0.11 Earth.
In 1955, American astronomers M. Walker and R. Hardy, using photoelectric observations of the brightness of the planet, calculated the period of rotation of Pluto around its axis - 6 days 9 hours 16.9 minutes. 12 years later, the Soviet astronomer R.I. Kiladze confirmed this period from his own observations. The nature of the fluctuations turned out to be unusual: a slow increase in the brightness of the planet, occupying 0.7 periods, was replaced by a rapid decrease. After 10 years, the nature of Pluto's brightness fluctuations has not changed, but ... Pluto has become 0.1 magnitude weaker, although during this time it has approached the Sun and the Earth, which means it should have become brighter on the contrary. By 1971, Pluto had weakened by another 0.1 magnitude.
On June 22, 1978, J. W. Christie, looking through the pictures of Pluto, obtained in April-May of the same year on the 155-cm reflector of the Naval Observatory in Flagstaff (Arizona), drew attention to the "protrusion" visible in some pictures of the planet. Christie correctly interpreted it as a close satellite. The discovery was confirmed by astronomer J. A. Graham with a 4-meter telescope at the Cerro Tololo Observatory (Chile).
The pictures Christie used to discover CharonA colleague of the discoverer R. S. Harrington discovered the equality of the periods of rotation of the planet and the satellite. It turned out that Pluto and its satellite are in 1:1 resonance and both are turned to each other by only one side. At the same time, Christie was able to find a satellite in images taken at the same observatory and taken eight and twelve years before him. As a discoverer, he proposed a name for the satellite - Charon. According to Greek mythology, this was the name of the carrier of the souls of the dead across the river Styx to the underworld of Pluto.
By the end of the 70s, the sizes of Pluto and Charon were still very uncertain: 1000-4000 and 500-2000 km, respectively. Further studies have made it possible to significantly refine these values. On April 6, 1980, a magnitude 12 star passed very close to Pluto, creating an occultation of 50 seconds. But it was not Pluto that closed the star (located one arc second from the star and having a diameter of 0.14 "), but Charon. Employees of the US Naval Observatory obtained the values \u200b\u200bof Charon's diameter of 1200 km, and the inclination of the orbit to the plane of Pluto's orbit of 65 degrees.
Research into Charon's orbit was also continued by French researchers. In September 1980, astronomers D. Bonnot and R. Foix took a series of photographs, processing them on a computer, and obtained the radius of Charon's orbit at 19,000 km. The refinement of the orbit made it possible to accurately determine the mass of the entire Pluto-Charon system, it remained to accurately determine the diameter of Pluto. And here the astronomer was unusually lucky. Charon was discovered just 7 years before the beginning of the period of mutual eclipses in the Pluto-Charon system, which occurred in 1985-1990. This rare event happens once every 124 years. During it, Charon passes behind Pluto once in its orbital period, and once in front of it. Observation of these occultations made it possible to determine the sizes of Pluto and Charon with an accuracy of several kilometers. A significant amount of data has also been collected on the albedo of the surfaces of Pluto and Charon facing each other. The first eclipses took place in the north polar region of Pluto, subsequent ones across the equator, to the south polar zone. These and subsequent observations have shown that the surface of Pluto is the most contrast in the solar system after the Earth and significantly more contrast than Mars.
An independent determination of the size of Pluto was carried out in 1988 during its occultation of a star. At the same time, an extended rarefied atmosphere was discovered near the planet.
Back in 1976, using a 4-meter reflector at the Kitt Peak Observatory, the American astronomer D. Cruikshank and his colleagues, studying the infrared spectrum of Pluto, discovered in it lines characteristic of methane ice. Earlier in 1970, J. Fix, J. Neff and L. Kelsey on a 60-cm reflector with a spectrophotometer found signs of absorption bands of iron ions in the spectrum and came to the conclusion that the rocks of the planet are enriched in iron. Then, in 1980, Yu. Fink (USA) discovered methane absorption bands in the spectrum of Pluto, suggesting the presence of a methane atmosphere. In 1992, frozen nitrogen and carbon monoxide were discovered on the surface of the planet. The 1988 coverage made it possible to estimate the pressure on the surface at 0.15 Pa, and the other two in 2002 (in July and August 20) observed by astronomers from many observatories gave a value of 0.3 Pa. This is surprising since Pluto passed perigee on September 5, 1989 and is now moving away from the Sun. One explanation for this effect is that in 1987 the southern polar region of the planet emerged from the perennial shadow, and evaporating nitrogen increased the density of the atmosphere.
Ground-based infrared observations gave a surface temperature of -238 degrees Celsius (35K), but observations made in the late 90s by the ISO space-based infrared observatory revealed warmer areas with temperatures up to -208 degrees Celsius (65K). The overlay of optical and infrared photographs made it possible to determine that warmer areas correspond to darker rocks, and colder areas correspond to lighter ones.
The occultation of Charon by the star 2UCAC 2625 7135 14th magnitude on July 11, 2005, observed in South America by 3 independent groups of astronomers, made it possible to further refine its radius and explore the possibility of having a rarefied atmosphere.
The Hubble Space Telescope began observing Pluto in 1994. With its help, it was possible to compile the first two maps of the surface of Pluto, in 1996 - black and white, and in 2005 - color, with a resolution of up to 100 km per pixel! And, finally, having examined the images of the space telescope for May 15, 2005 and June 14, 2002, a group of astronomers managed to detect two new satellites of Pluto with a brightness of about 23 magnitudes and a size of about 50-200 km. The studies carried out allow us to say that Pluto has no other satellites larger than 15 kilometers in diameter.
More detailed information about the new satellites will be obtained during further Hubble observations of Pluto in February 2006.
