In August 2006, incredible news thundered: the solar system lost one of the planets! Here you will really be on your guard: today one planet has disappeared, tomorrow another, and there, you see, the turn will reach the Earth!

However, there was no reason to panic then, nor now. It was only about the decision of the International Astronomical Union, which, after long disputes, deprived Pluto of the status of a full-fledged planet. And, contrary to misconceptions, on that day the solar system did not shrink, but, on the contrary, expanded unimaginably.

Briefly:
Pluto is too small for the planet. There are celestial bodies that were previously considered asteroids, although they are the same size, or even larger, than Pluto. Now both they and Pluto are called dwarf planets.

Search for wanderers

The discovery of Pluto for a long time considered the ninth planet solar system, has a history.

Before the advent of telescopes, mankind knew five celestial bodies called planets (translated from Greek - “wanderers”): Mercury, Venus, Mars, Jupiter, Saturn. In four centuries, two more have been discovered major planets: Uranus and Neptune.

The discovery of Uranus is remarkable in that it was made by an amateur music teacher William Herschel. On March 13, 1781, he was surveying the sky and suddenly noticed a small yellow-green disk in the constellation Gemini. At first, Herschel thought he had discovered a comet, but observations by other astronomers confirmed that a real planet had been discovered with a stable elliptical orbit.

Herschel wanted to name the planet Georgia after King George III. But the astronomical community has decided that the name of any new planet must match the others, that is, come from classical mythology. As a result, the planet was named Uranus in honor of the ancient Greek god of heaven.

Observations of Uranus revealed an anomaly: the planet stubbornly refused to follow the laws of celestial mechanics, deviating from the calculated orbit. Twice astronomers calculated models of the motion of Uranus, adjusted for the gravity of other planets, and twice he “deceived” them. Then there was an assumption that Uranus is influenced by another planet located beyond its orbit.

On June 1, 1846, an article by the mathematician Urbain Le Verrier appeared in the journal of the French Academy of Sciences, where he described the expected position of a hypothetical celestial body. On the night of September 24, 1846, at his prompting, the German astronomers Johann Galle and Heinrich d'Arre, without spending much time searching, discovered an unknown object, which turned out to be big planet and was named Neptune.

Planet X

The discovery of the seventh and eighth planets in just half a century has tripled the boundaries of the solar system. Satellites were discovered near Uranus and Neptune, which made it possible to accurately calculate the masses of the planets and their mutual gravitational influence. Based on these data, Urbain Le Verrier built the most accurate model of orbits at that time. And again, reality diverged from the calculations! New riddle inspired astronomers to search for a trans-Neptunian object, which became conventionally called "planet X".

The glory of the discoverer went to the young astronomer Clyde Tombaugh, who abandoned mathematical models and began to study the sky with the help of a photographic refractor. On February 18, 1930, comparing photographic plates in January, Tombaugh discovered the displacement of a faint star-shaped object - it turned out to be Pluto.

Astronomers soon determined that Pluto was a very small planet, smaller than the Moon. And its mass is clearly not enough to influence the movement of the huge Neptune. Then Clyde Tombaugh launched a powerful search program for another "planet X", but, despite all efforts, it was not possible to find it.

We know a lot more about Pluto today than we did in the 1930s. Thanks to many years of observations and orbiting telescopes, it was possible to find out that it has a very elongated orbit, which is inclined to the plane of the ecliptic (Earth's orbit) at a significant angle - 17.1 °. This unusual property has allowed speculation as to whether Pluto is home planet The solar system or it is accidentally attracted by the gravity of the Sun (for example, this hypothesis is considered by Ivan Efremov in the novel "The Andromeda Nebula").

Pluto has small satellites, and many of them have been discovered quite recently. There are five of them: Charon (discovered in 1978), Hydra (2005), Nikta (2005), P4 (2011) and P5 (2012). The presence of such a complex system of satellites suggested that Pluto has rarefied rings of debris - such are always formed when small bodies collide in orbits around planets.

Maps compiled using data from the Hubble orbiting telescope showed that Pluto's surface is not uniform. The part facing Charon contains predominantly methane ice, while on the opposite side more ice from nitrogen and carbon monoxide. At the end of 2011, complex hydrocarbons were discovered on Pluto - this allowed scientists to assume that the simplest forms of life exist there. In addition, the rarefied atmosphere of Pluto, consisting of methane and nitrogen, has noticeably “swollen” in recent years, which means that there are climate changes on the planet.

What was Pluto called?

Pluto was named on March 24, 1930. Astronomers voted on a shortlist containing three final options: Minerva, Kronos and Pluto.

The third option turned out to be the most suitable - the name of the ancient god of the kingdom of the dead, also known as Hades and Hades. It was proposed by Venetia Burney, an eleven-year-old schoolgirl from Oxford. She was interested not only in astronomy, but also in classical mythology, and decided that the name Pluto best suits the dark and cold world. The name came up in a conversation with her grandfather Falconer Meidan, who had read about the planet's discovery in a magazine. He conveyed Venice's proposal to Professor Herbert Turner, who, in turn, telegraphed his colleagues in the United States. For her contribution to the history of astronomy, Venetia Burney received a prize of five pounds sterling.

Interestingly, Venice survived until the moment when Pluto lost its status as a planet. When asked about her attitude to this "downgrade", she replied: "At my age, there is no such debate anymore, but I would like Pluto to remain a planet."

Edgeworth-Kuiper Belt

By all indications, Pluto is a normal planet, albeit a small one. Why did astronomers react so unfavorably to him?

The search for a hypothetical "Planet X" continued for decades, which led to many interesting discoveries. In 1992, a large cluster of small bodies, similar to asteroids and comet nuclei, was discovered beyond the orbit of Neptune. The existence of a belt of debris left over from the formation of the solar system was predicted long before by the Irish engineer Kenneth Edgeworth (in 1943) and the American astronomer Gerard Kuiper (in 1951).

The first trans-Neptunian object belonging to the Kuiper belt was discovered by astronomers David Jewitt and Jane Lu, observing the sky with the latest technologies. On August 30, 1992, they announced the discovery of the body 1992 QB1, which they named Smiley after the hero of the popular detective John Le Carré. However, this name is not officially used, since there is already an asteroid Smiley.

By 1995, seventeen more bodies had been discovered beyond the orbit of Neptune, eight of them beyond the orbit of Pluto. By 1999 total registered objects of the Edgeworth-Kuiper belt has exceeded a hundred, by now - over a thousand. Scientists believe that in the foreseeable future it will be possible to identify more than seventy thousand (!) Objects larger than 100 km. It is known that all these bodies move in elliptical orbits, like real planets, and a third of them have the same orbital period as Pluto (they are called “plutinos” - “plutons”). The objects of the belt are still very difficult to classify - it is only known that they have sizes from 100 to 1000 km, and their surface is dark with a reddish tint, which indicates an ancient composition and the presence of organic compounds.

By itself, the confirmation of the Edgeworth-Kuiper hypothesis could not cause a revolution in astronomy. Yes, now we know that Pluto is not a lonely wanderer, but the neighboring bodies are not able to compete with it in size, and besides, they have no atmosphere and satellites. The scientific world could continue to sleep peacefully. And then something terrible happened!

Dozens of Plutos

Mike Brown - "the man who killed Pluto"

Astronomer Mike Brown, in his memoirs, claims that even as a child, through observations, he independently discovered the planets, unaware of their existence. When he became a specialist, he dreamed of the greatest discovery - "Planet X". And he opened it. And not even one, but sixteen!

The first trans-Neptunian object, designated 2001 YH140, was discovered by Mike Brown with Chadwick Trujillo in December 2001. It was a standard celestial body of the Edgeworth-Kuiper belt with a diameter of about 300 km. Astronomers continued their vigorous search, and on June 4, 2002, the team discovered the much larger object 2002 LM60, 850 km in diameter (now estimated to be 1,170 km in diameter). That is, the size of 2002 LM60 is comparable to the size of Pluto (2302 km). Later, this body, which looks like a full-fledged planet, was called Quaoar - after the creator god worshiped by the Tongva Indians of Southern California.

Further more! November 14, 2003 Brown's group discovers the trans-Neptunian object 2003 VB12, which is named Sedna - in honor of the Eskimo goddess of the sea, who lives at the bottom of the North Arctic Ocean. At first, the diameter of this celestial body was estimated at 1800 km; additional observations with the Spitzer Orbital Telescope reduced the estimate to 1,600 km; on the this moment it is believed that the size of Sedna is 995 km. Spectroscopic analysis has shown that Sedna's surface is similar to some other trans-Neptunian objects. Sedna moves in a very elongated orbit - scientists believe that it was once influenced by a star that passed by the solar system.

On February 17, 2004, Mike discovers an object 2004 DW, named Orc (deity of the underworld in Etruscan and Roman mythology), with a diameter of 946 km. Spectral analysis of Ork showed that he is covered water ice. Most of all, Orc is similar to Charon - a satellite of Pluto.

On December 28, 2004, Brown discovers object 2003 EL61, named Haumea (Hawaiian Goddess of Fertility), about 1300 km in diameter. Later it turned out that Haumea rotates very quickly, making one revolution around its axis in four hours. Hence, its shape must be strongly elongated. Modeling showed that in this case, the longitudinal size of Haumea should be close to the diameter of Pluto, and the transverse size - half as much. Perhaps Haumea appeared as a result of the collision of two celestial bodies. Upon impact, some of the light components evaporated and were ejected into space, subsequently forming two satellites: Hiiaka and Namaka.

goddess of discord

Mike Brown's finest hour struck on January 5, 2005, when his team discovered a trans-Neptunian object estimated to be 3000 km in diameter (later measurements gave a diameter of 2326 km). Thus, in the Edgeworth-Kuiper belt, a celestial body was found that is definitely larger than Pluto in size. Scientists made a noise: finally, the tenth planet is open!

Astronomers gave the new planet the unofficial name Xena in honor of the heroine. And when Xena found a companion, they immediately named him Gabriel - that was the name of Xena's companion. The International Astronomical Union could not accept such "frivolous" names, so Xena was renamed Eridu ( Greek goddess discord), and Gabriel - in Dysnomia (the Greek goddess of lawlessness).

Eris has indeed caused discord among astronomers. Logically, Xena-Eris should have been immediately recognized as the tenth planet, and the Michael Brown group should have been entered into the annals of history as its discoverers. But it was not there! Previous discoveries have indicated that perhaps dozens more objects comparable in size to Pluto are hiding in the Edgeworth-Kuiper belt. What is easier - multiplying the number of planets, rewriting astronomy textbooks every couple of years, or throwing out Pluto from the list, and with it all the newly discovered celestial bodies?

The verdict was passed by Mike Brown himself, having discovered on March 31, 2005 the object 2005 FY9 with a diameter of 1500 km, named Makemake (the creator god of mankind in the mythology of the Rapanui people, the inhabitants of Easter Island). The patience of the colleagues ran out, and they gathered at the conference of the International Astronomical Union in Prague to determine once and for all what a planet is.

Previously, a planet could be considered a celestial body that revolves around the Sun, is not a satellite of another planet and has sufficient mass to acquire a spherical shape. As a result of the debate, astronomers added another requirement: that the body "clear" the surroundings of its orbit from bodies of comparable size. Pluto did not meet the last requirement and was deprived of the status of a planet.

He migrated to the list of "dwarf planets" (from the English "dwarf planet", literally - "dwarf planet") at number 134340.

This decision drew criticism and ridicule. Pluto scientist Alan Stern said that if this definition were applied to Earth, Mars, Jupiter and Neptune, in whose orbits asteroids were found, then they should also be stripped of the title of planets. In addition, according to him, less than 5% of astronomers voted for the decision, so their opinion cannot be considered universal.

However, Mike Brown himself accepted the definition of the International Astronomical Union, content that the discussion had finally ended to everyone's satisfaction. And indeed - the storm subsided, the astronomers went to their observatories.

Deprived of the status of a planet, Pluto has become an inexhaustible source for Internet creativity

Society reacted differently to the decision of the International Astronomical Union: someone did not attach importance, but someone was convinced that scientists were fooling around. AT English language the verb “to pluto” (“to pluto”) appeared, recognized as the word of 2006 according to the American Dialectological Society. The word means "decrease in value or value."

The authorities of the states of New Mexico and Illinois, where Clyde Tombo lived and worked, decided by law to retain the status of a planet for Pluto and declared March 13 the annual Day of the planet Pluto. Ordinary citizens responded with both online petitions and street protests. It was difficult for people who had considered Pluto a planet all their lives to get used to the decision of astronomers. In addition, Pluto was the only planet discovered by an American.

Who benefits?

Pluto is the only one who lost in status. The rest of the dwarf planets were previously classified as asteroids. Among them is Ceres (named after the Roman goddess of fertility), discovered back in 1801 by the Italian astronomer Giuseppe Piazzi. For some time, Ceres was considered the very missing planet between Mars and Jupiter, but later it was attributed to asteroids (by the way, this term was specially introduced precisely after the discovery of Ceres and neighboring large objects). By the decision of the astronomical union in 2006, Ceres began to be considered a dwarf planet.

Ceres, whose diameter reaches 950 km, is located in the asteroid belt, which seriously complicates its observation. It is hypothesized to have an icy mantle or even oceans of liquid water below the surface. A qualitative step in the study of Ceres was the mission of the Dawn interplanetary apparatus, which reached the dwarf planet in the fall of 2015.

We won't be found!

The Pioneer 10 and Pioneer 11 interplanetary spacecraft, launched in the early 1970s, carried aluminum plates with a message to aliens. In addition to images of a man, a woman and an indication of where to look for us in the galaxy, there was a diagram of the solar system. And it consisted of nine planets, including Pluto.

It turns out that if someday the "brothers in mind", guided by the "Pioneers" scheme, want to find us, they are very likely to pass by, confused in the number of planets. However, if they are evil alien invaders, you can always say that we deliberately confused them.

∗∗∗

Today it seems unlikely that the classification of Pluto, Eris, Sedna, Haumea and Quaoar will ever be revised. And only Mike Brown is not discouraged - he is sure that in the coming years, a celestial body the size of Mars will be discovered at the far edge of the Edgeworth-Kuiper belt. It's terrible to imagine what will happen then!

• Michael Brown "How I Killed Pluto and Why It Was Inevitable"
• David A. Weintraub “Is Pluto a planet? Journey through the Solar System (Is Pluto a Planet?: A Historical Journey through the Solar System)
• Elayne Scott When Is a Planet Not a Planet?: The Story of Pluto
• David Aguilar Thirteen Planets. A Modern View of the Solar System (13 Planets: The Latest View of the Solar System)

You have no idea how many people were upset when the decision was made to stop considering Pluto a planet in the solar system. Kids whose favorite cartoon dog, Pluto, is suddenly named after who knows what. Recall that in ancient Greek mythology this is one of the names of the god of death. Chemists and nuclear physicists were saddened, who called this name plutonium - a radioactive element capable of destroying all of humanity. And what about astrologers? The unfortunate charlatans have fooled people for decades, describing how strong this degraded object has on their fate and character, and it’s good if indignant clients do not present material claims to them.

When did Pluto stop being considered a planet?

Be that as it may, Pluto ceased to be considered a planet in 2006. We must come to terms with this and live with the awareness of this fact. Does not work? Okay, then let's forget about feelings and try to look at the situation from the point of view of logic, which is what science always calls us to do.

The demolition of Pluto took place at the 26th General Assembly of the International Astronomical Society, held in Prague, and this decision caused a lot of controversy and objections. Some scientists wanted to keep it as a planet, but the only argument they could make to justify their desire was that "it would break tradition." The fact is that there is not, and never has been, any scientific reason to consider Pluto a planet. This is just one of the objects of the Kuiper belt - a huge cluster of heterogeneous celestial bodies located beyond the orbit of Neptune. There are about a trillion of them there, these objects. And all of them are blocks of stone and ice, like, in fact, Pluto. It's just the first one we've seen.

It is, of course, very large compared to most of its neighbors, but it is not the largest object in the Kuiper belt. Such is Eris, which, if inferior to Pluto in size, is quite a bit, so small that the debate about which of them is larger continues to this day. But it is a quarter heavier. This object is located twice as far from the Sun as Pluto. There are many other similar celestial bodies in the solar system. These are Haumea, and Makemane, and Ceres, which is located in the asteroid belt between Mars and Jupiter. According to scientists, in total we may have about a hundred such strong men. Waiting to be noticed.

There is no fantasy here. No animators, no chemists. Astrologers should have enough, but few serious people care about their interests. This is exactly the main reason why we stopped considering Pluto a planet. Because, together with him, we, in theory, should raise so many celestial bodies to this rank that the very word “planet” will lose its current meaning. In this regard, in the same 2006, astronomers defined clear criteria for objects claiming this status.

What are the criteria for a “planet”?

They must orbit the Sun, have enough gravity to bring themselves into a more or less spherical shape, and almost completely clear their orbit of other objects. Pluto cut off at the last point. Its mass is only 0.07% of the mass of everything that is on its circular trajectory. To give you an idea of ​​how insignificant this is, let's say that the mass of the Earth is 1,700,000 times the mass of other matter in its orbit.

I must say that the International Astronomical Society turned out to be not entirely heartless. It came up with a new category for celestial bodies, satisfying only the first two criteria. Now they are dwarf planets. And in deference to the place that Pluto once occupied in our worldview and in our culture, it was decided to call the dwarf planets farther than Neptune “plutoids”. Which, of course, is pretty sweet.

And in the same year that astronomers decided that Pluto could no longer be called a planet, NASA launched spacecraft“New Horizons” (New Horizons), whose flight mission includes a visit to this celestial body. As of this moment in time, this interplanetary station has completed its task by transmitting to Earth a lot of valuable data about Pluto, as well as picturesque photographs of this dwarf planet. Don't be lazy, find them online.
Let's hope that humanity's interest in Pluto does not end there. It is, after all, on our way to other stars and galaxies. We're not going to sit in our solar system forever.

Today, astrophysics is considered one of the most controversial and dynamically developing sciences. If classical and academic truths that have become statements and axioms dominate in physics and mathematics, then in astronomy scientists constantly have to deal with something new, proving the opposite for established statements. Current technical advances allow scientific community conduct a more detailed study and exploration of space, therefore, more and more often in modern science and there are situations similar to the one that has developed around Pluto.

Since 1930, since its discovery, for some time Pluto was considered a full-fledged planet, having the ninth serial number. However, the celestial body was in this status for a short time - only 76 years. In 2006, Pluto was excluded from the list of planets in the solar system, moving into the category of dwarf planets. This move by the scientific community disrupted the classical view of the solar system, setting a precedent in modern science. What was the reason for modern science to make such a radical decision and what can we face tomorrow, continuing to study the near space?

The main characteristics of the new dwarf planet

To come to a decision to transfer the ninth planet to the category of dwarf planets, humanity took a little time. A period of 76 years, even by earthly standards, is considered short enough for significant changes to occur in the astrophysical laboratory. However, the rapid development of science and technology over the past years has cast doubt on the seemingly indisputable fact that Pluto is a planet.

Even 15-20 years ago, in all school textbooks on astronomy, in all planetariums, Pluto was spoken of as a full-fledged planet in the solar system. Today, this celestial body has been downgraded and is considered a dwarf planet. What is the difference between these two categories? What does Pluto lack to be considered a full-fledged planet?

In terms of size, the ex-planet is really very small. The size of Pluto is 18% of the Earth's, 2360 km versus 12742 km. However, even with such a small size, Pluto had the status of a planet. This situation looked somewhat unusual, given the fact that there are many natural satellites in the solar system that are much larger. What are the giant satellites of Jupiter and Saturn - Ganymede and Titan - exceeding even Mercury in size. In terms of its physical parameters, Pluto is inferior even to our Moon, whose diameter is 3,474 km. It turns out that the size of a celestial body is not always the main criterion for determining its status in astrophysics.

The small size of Pluto did not prevent astronomers from theoretically recognizing its presence for a long time. Long before its discovery, this celestial object had a modest name - Planet X. In 1930, the American astronomer Clyde Tombaugh visually discovered that the star he observed in the night sky was moving in its own planetary orbit. Then scientists considered that in front of them was the ninth planet of the solar system, the orbit of which is the boundary of our solar system. The scientific community was not embarrassed by either the size of the newly discovered celestial body or its orbital parameters. To top it all off new planet was given a solid name - Pluto, given in honor of the ancient Greek god, the ruler of the underworld. The distance from the Sun to the ninth planet was 5.9 billion km. These parameters were then used for a long time to determine the scale of our solar system.

The one who discovered the planet did not have the technical ability to look deeper into space and put everything in its place. At that time, astrophysicists had limited knowledge and information about the border regions of our solar system. They did not know where near space ends and boundless outer space begins.

Why is Pluto not a planet?

Despite the fact that the former ninth planet was tiny in size, it was she who was considered the last and only large celestial body located beyond the orbit of Neptune. The emergence of more powerful optical telescopes in the second half of the 20th century completely changed the idea of outer space surrounding our star system. In addition to the fact that scientists managed to find their own natural satellites in baby Pluto, the status of the ninth planet was shaken.

The main reason for the changed attitude of scientists to a small planet was the discovery at a distance of 55 AU. from the Sun a large cluster of celestial bodies of various sizes. This region extended just beyond the orbit of Neptune and became known as the Kuiper belt. Subsequently, in this region of space, it was possible to detect numerous objects with a diameter exceeding 100 km, and similar in composition to Pluto. It turned out that the small planet is just one of many celestial bodies revolving in such a tight circle. This was the main argument in favor of the fact that Pluto is not the last large celestial body discovered beyond the orbit of Neptune. The discovery in the Kuiper belt of the small planet Makemake in 2005 was the first sign. Following her in the same year, astrophysicists discovered three more large celestial bodies in the Kuiper belt, which received the status of trans-Neptunian objects - Haumea and Sedna. In size, they were slightly inferior to Pluto.

For astrophysicists, 2005 was a turning point. The discovery of numerous objects outside the orbit of Neptune gave scientists reason to believe that Pluto is not the only large celestial body. It is possible that in this region of the solar system there are objects similar to or larger than the ninth planet. The received accurate information about Eris put an end to the disputes about the fate of Pluto. It turned out that Eris is not only larger than the planetary disk of Pluto (2600 km versus 2360 km), but also has a whole quarter more mass.

The availability of such information led to the fact that the scientific community had to urgently look for a way out of this situation. Among scientists and astrologers on international conferences real battles unfolded on this occasion. After the very first speeches by scientists and astrologers, it became clear that Pluto could not be called a planet. They have accumulated a lot of material in favor of the fact that in the Kuiper belt, along with Pluto, there are other objects with similar astrophysical parameters and characteristics. Proponents of the revision of the concept of the classical structure of the solar system suggested that all trans-Neptunian objects be separated into a separate class of celestial bodies in the solar system. According to this concept, Pluto became an ordinary trans-Neptunian object, finally losing its status as the ninth planet of our star system.

The members of the International Astronomical Union, who gathered in Prague for the XXVI General Assembly, put an end to this issue. In accordance with the decision General Assembly Pluto has been stripped of planet status. On top of that, a new definition has appeared in astronomy: dwarf planets are celestial bodies that meet certain criteria. These included Pluto, Eris, Makemake and Haumeu and the largest Asteroid - Ceres.

It is believed that Pluto, unlike other large celestial bodies, does not meet one of the four criteria according to which a celestial body can be classified as a planet. For the former ninth planet, the following features are characteristic:

• the presence of a sufficiently large mass;
• Pluto is no one's moon, and itself has four natural satellites;
• the celestial body has its own orbit, in which Pluto revolves around the sun.

The last fourth criterion, which allows Pluto to be classified as a planet, is absent in this case. The celestial body, neither before nor after, has been able to clear the orbital space around itself. This was the main argument in favor of the fact that Pluto is now a dwarf planet, a celestial body with a completely different status.

In support of this concept, a version is given about the formation of the planet, when it becomes the dominant object in a certain orbit, subordinating all other bodies to its own gravitational field. Subsequently, a large celestial body must either absorb smaller objects, or push them beyond the boundaries of its own gravity. Judging by the size and mass of Pluto, nothing like this happened to the ex-planet. A small planet has a mass equal to only 0.07 of the mass of all space objects included in the Kuiper belt.

Basic information about Pluto

In the old days, when Pluto was a full member of the club of planets, he was ranked among the planets terrestrial group. Unlike the gas giants Jupiter, Saturn, Uranus and Neptune, the former planet has a solid surface. Consider with close range The surface of the most distant object in the solar system was only possible in 2018, when the New Horizons space probe flew 12,000 km from the underground god. With the help of this automatic probe, a person first saw the surface of a dwarf planet in detail and was able to draw short description this celestial body.

A small planet, which is visible in the sky as a barely visible star, runs around the Sun in 249 years. At perihelion, Pluto approaches it at a distance of 29-30 AU, at aphelion the dwarf planet moves away at a distance of 50-55 AU. Despite such vast distances, Pluto, unlike its neighbors Neptune and Uranus, is open to study. ice world. The baby rotates around its own axis at a speed of 6 days and 9 hours, although its orbital speed is quite small - only 4.6 km / s. For comparison, Mercury's orbital speed is 48 km/s.

The area of ​​the planet is 17.7 million square meters. kilometers. Almost over the entire area, the surface of the planetary disk is available for viewing and represents the kingdom eternal ice and cold. It is assumed that Pluto consists of frozen water ice, nitrogen and silicate rocks. In other words, it's huge ice block, the density of which is 1.860 ± 0.013 g/cm3. Average temperatures on the planet are extreme: -223 degrees Celsius below zero. A weak gravitational field and low density have led to the fact that on Pluto the minimum value of the acceleration of free fall is 0.617 m/s2.

Judging by the images, there are depressions and mountains on Pluto, the height of which can reach 3-3.5 km. In addition to the solid surface, Pluto also has its own atmosphere. A weak gravitational field does not allow the planet to have an extensive air-gas layer. The thickness of the gas layer is only 60 km. These are mainly gases evaporating from the icy surface of Pluto under the influence of hard ultraviolet radiation.

New discoveries from the life of Pluto

In addition to all the information available about Pluto, an atmosphere has recently been discovered on Pluto's moon Charon. This satellite is slightly inferior in size main planet, and scientists have their own opinions on this matter.

The last fact is quite curious. There is a version that Pluto and Charon are a typical double planet. This is the only case in our solar system when the parent celestial body and its satellite are similar in many respects to each other. Whether this is so - time will tell, while humanity continues to collect Interesting Facts about the Kuiper belt, where, along with Pluto, there are many more curious space objects.

If you have any questions - leave them in the comments below the article. We or our visitors will be happy to answer them.

Some say with all certainty that all the planets are just clumps of matter revolving around the Sun, having their own indicators: diameter, mass, volume and area. And Pluto is no exception. Judge for yourself:

So why did Pluto, having been "born", not bother to be a planet until its "death"? It turns out that in order to be officially called a planet of the solar system, it is necessary that its data and functions meet certain conditions, namely:

1. revolved in orbit around the sun;
2. so that they take a shape close to a ball under the influence of their own gravitational forces (for this you need to be massive);
3. the ability to clear the vicinity of its orbit from other objects by gravity (i.e., when interacting with smaller objects, they must either push them out with their gravity or absorb them).
4. should not be satellites of other planets, and should not themselves have one (and the New Horizons spacecraft photographed all five of Pluto's moons).

Why is Pluto not a planet? They "pumped up" the correspondence to the points for clearing the surroundings and the presence of satellites. It is so small that its mass is only 0.07 of all objects, and this is not enough to clear the area from asteroids.

For such planets, scientists introduced a new definition: they began to be called "dwarf". This included Pluto. Another version of why he is so "offended." Astronomers claim that its orbit is very elongated and too inclined with respect to the plane in which the Earth's orbit lies (by 17 °; next comes Mercury ─ a deviation of only 7 °). As for elongation, yes, Pluto's orbit is elongated, but, for example, the same Mercury is elongated in almost the same way.

And the message that NASA managed to open in 2003 added fuel to the fire. celestial body UB13 called Eris, different from the claimed planet big size(2,600 km) and a mass that is 25% higher than its mass. A real "bombshell" effect! Pluto is not a planet (yet!), as there is talk of returning this status to it, but it, just as before, revolves with a period of 248 Earth years around the Sun and will do so for a very long time.

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The ninth and most distant planet in the solar system is Pluto. In 2006, the International Astronomical Union excluded this space object from the list of planets. Despite this fact, Pluto is still considered a small (dwarf) planet of the Kuiper belt, and is the most famous planet dwarf type, as well as the largest celestial body, which is located further than Neptune and the tenth largest and most massive object among those that revolve around the Sun (not counting planetary satellites). The decision to take the ninth planet is rather controversial, in scientific circles there is an opinion that it is necessary to cancel the decision of the Union of Astronomers. The planet has one large satellite and four smaller ones. Symbol of the cosmic body - intertwined letters P and L.

Opening

Interesting facts about Pluto related to discovery and research. At first, the ninth planet was called Planet X. But an Oxford schoolgirl came up with modern name- Pluto, for this she received a prize - 5 pounds sterling. The name was positively received by the scientific community, as it is traditionally associated with ancient mythology ( ancient greek god the underworld), as well as the name of many other planets and space objects.

The orbit of the planet could be calculated using mathematical calculations, its existence was predicted at the beginning of the twentieth century by the American astronomer Percival Lowell, so the object was first called Percival. But the planet itself was found not thanks to complex calculations, but thanks to K. Tombo, who managed to find such a small object in the sky among millions of stars in 1930.

A distant block of stones and ice that makes up the planet can only be seen through a telescope with 200 mm lenses, and the first time it is unlikely to be able to detect it, since the planet moves very slowly and you need to carefully compare it with other celestial bodies on the stellar map. Venus, for example, is easy to detect not only because of its brightness, but also because of its rapid movement relative to the stars.

Due to the remoteness directly to Pluto long time not a single spacecraft flew up. But on July 14, 2015, the American spacecraft New Horizons passed at a distance of 12.5 thousand kilometers from the surface of the planet, taking high-quality images of the surface.

Since the discovery for 80 years, Pluto was considered a full-fledged planet, but astronomers, after conferring, announced in 2006 that this is not an ordinary planet, but a dwarf one with the official name "asteroid number 134340", there are two dozen such dwarf-type planets. This decision may be rash, as this celestial object remains the tenth largest in the solar system.

Despite the fact that the planet moves somewhat chaotically, it has two poles - north and south. This fact, coupled with the fact that there are satellites and an atmosphere, is proof for many scientists that this is a real planet. Some researchers believe that the object was called dwarf because of its great distance from the Sun and placement in the Kuiper belt, and not at all because of its size.

Properties

Planet Pluto - interesting facts about the properties of the planet. This is the last planet of the solar system - the distance from our star ranges from 4.7 to 7.3 million kilometers, this distance the light overcomes more than five hours. The planet is 40 times farther from the Sun than the Earth.

A year on Pluto lasts 248 Earth years - it is during this time that the planet makes one revolution in the solar orbit. The orbit is very elongated, it is also in a different plane relative to the orbits of other planets in the solar system.

A day lasts almost an Earth week, revolutions around its axis are made in the opposite direction than that of the Earth, so the Sun rises in the west, sunset is observed in the east. There is little sunlight even during the day, therefore, standing on the planet, you can observe the starry sky around the clock.

The composition of the atmosphere, which was discovered in 1985, is carbon monoxide, nitrogen and methane. Of course, a person cannot breathe such a gas mixture. The presence of an atmosphere (which, perhaps, is common to the planet itself and its satellite Charon) is a hallmark of Pluto, which was deprived of the status of a real planet and demoted to a dwarf planet. None of the dwarf planets have an atmosphere.

Among the planets, Pluto is the smallest, weighing about 0.24 percent of the Earth's mass.

Pluto and Earth rotate in opposite directions from each other.

The satellite is Charon, which is almost the same size as Pluto (half the size, but still the difference is insignificant, as for a satellite). Therefore, the outermost planet in the solar system is often called a double.

This planet is the coldest average temperature minus 229 degrees Celsius.

Despite its small size (six times less than the Moon in weight), this celestial body has several satellites - Charon, Nix, Hydra, P1.

The planet is made up of rocks and ice blocks.

Named after Pluto chemical element plutonium.

The planet has a very long rotation period around the Sun - from the time it was discovered until 2178, it will for the first time make a circle around the center of the solar system.

The dwarf planet will reach its maximum distance from the Sun in 2113.

The force of gravity is much less than Earth's - 45 kilograms on Earth turn into 2.75 kilograms on Pluto.

The planet cannot be seen without optical devices, and even when approaching the Earth at a minimum distance, it still cannot be seen with the naked eye.

The distance from the Sun is so great that the heavenly body, which roasts Venus and gives enough heat to the Earth, from the surface of Pluto looks like a small dot, in fact - like a big star.

Since the concentration of objects in space is small, large bodies influence each other with their gravity. Astronomers have foreseen such an interaction for Pluto, Uranus and Neptune. But the mass of Pluto turned out to be so small relative to a large orbit that this planet has practically no effect on the nearest planets of the solar system.