The solar system is a group of planets revolving in certain orbits around a bright star - the Sun. This luminary is the main source of heat and light in the solar system.

It is believed that our system of planets was formed as a result of the explosion of one or more stars and this happened about 4.5 billion years ago. At first, the solar system was a collection of gas and dust particles, however, over time and under the influence of its own mass, the Sun and other planets arose.

Planets of the solar system

In the center of the solar system is the Sun, around which eight planets move in their orbits: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.

Until 2006, Pluto also belongs to this group of planets, it was considered the 9th planet from the Sun, however, due to its considerable distance from the Sun and its small size, it was excluded from this list and called a dwarf planet. Rather, it is one of several dwarf planets in the Kuiper belt.

All the above planets are usually divided into two large groups: the terrestrial group and the gas giants.

The terrestrial group includes such planets as: Mercury, Venus, Earth, Mars. They are distinguished by their small size and rocky surface, and in addition, they are located closer than the others to the Sun.

The gas giants include: Jupiter, Saturn, Uranus, Neptune. They are characterized big sizes and the presence of rings, which are ice dust and rocky pieces. These planets are made up mostly of gas.

Mercury

This planet is one of the smallest in the solar system, its diameter is 4,879 km. In addition, it is closest to the Sun. This neighborhood predetermined a significant temperature difference. average temperature on Mercury in the daytime is +350 degrees Celsius, and at night - -170 degrees.

1. Mercury is the first planet from the Sun.
2. There are no seasons on Mercury. The tilt of the planet's axis is almost perpendicular to the plane of the planet's orbit around the Sun.
3. The temperature on the surface of Mercury is not the highest, although the planet is located closest to the Sun. He lost first place to Venus.
4. The first research vehicle to visit Mercury was Mariner 10. It conducted a series of demonstration flybys in 1974.
5. A day on Mercury lasts 59 Earth days, and a year is only 88 days.
6. On Mercury, the most dramatic temperature changes are observed, which reach 610 ° C. During the day, the temperature can reach 430 ° C, and at night -180 ° C.
7. The force of gravity on the surface of the planet is only 38% of the Earth's. This means that on Mercury you could jump three times as high, and it would be easier to lift heavy objects.
8. The first telescope observations of Mercury were made by Galileo Galilei in the early 17th century.
9. Mercury has no natural satellites.
10. The first official map of the surface of Mercury was published only in 2009, thanks to data obtained from the Mariner 10 and Messenger spacecraft.

Venus

This planet is the second from the Sun. In size, it is close to the diameter of the Earth, the diameter is 12,104 km. In all other respects, Venus is significantly different from our planet. A day here lasts 243 Earth days, and a year - 255 days. The atmosphere of Venus is 95% carbon dioxide, which creates a greenhouse effect on its surface. This leads to the fact that the average temperature on the planet is 475 degrees Celsius. The atmosphere also includes 5% nitrogen and 0.1% oxygen.

1. Venus is the second planet from the Sun in the solar system.
2. Venus is the hottest planet in the solar system, although it is the second planet from the Sun. Surface temperature can reach 475°C.
   
3. The first spacecraft sent to explore Venus was launched from Earth on February 12, 1961 and was called Venera 1.
4. Venus is one of two planets that has a different direction of rotation than most planets in the solar system.
5. The orbit of the planet around the Sun is very close to circular.
6. The day and night temperatures of the surface of Venus are practically the same due to the large thermal inertia of the atmosphere.
7. Venus makes one revolution around the Sun in 225 Earth days, and one revolution around its axis in 243 Earth days, that is, one day on Venus lasts more than one year.
8. The first telescope observations of Venus were made by Galileo Galilei in the early 17th century.
9. Venus has no natural satellites.
10. Venus is the third brightest object in the sky, after the Sun and Moon.

Earth

Our planet is located at a distance of 150 million km from the Sun, and this allows us to create on its surface a temperature suitable for the existence of water in liquid form, and, therefore, for the emergence of life.

Its surface is 70% covered with water, and it is the only one of the planets that has such an amount of liquid. It is believed that many thousands of years ago, the steam contained in the atmosphere created the temperature on the Earth's surface necessary for the formation of water in liquid form, and solar radiation contributed to photosynthesis and the birth of life on the planet.

1. Earth is the third planet from the sun in the solar system.a;
2. One natural satellite revolves around our planet - the Moon;
   
3. Earth is the only planet not named after a divine being;
4. The Earth's density is the largest of all the planets in the solar system;
5. The speed of the Earth's rotation is gradually slowing down;
6. The average distance from the Earth to the Sun is 1 astronomical unit (a conventional measure of length in astronomy), which is approximately 150 million km;
7. The earth has a magnetic field strong enough to protect living organisms on its surface from harmful solar radiation;
8. The first artificial Earth satellite called PS-1 (The Simplest Satellite - 1) was launched from the Baikonur Cosmodrome on the Sputnik launch vehicle on October 4, 1957;
9. In orbit around the Earth, compared with other planets, there is the largest number of spacecraft;
10. Earth is the largest terrestrial planet in the solar system;

Mars

This planet is the fourth in a row from the Sun and is 1.5 times more distant from it than the Earth. The diameter of Mars is smaller than Earth's and is 6,779 km. The average air temperature on the planet ranges from -155 degrees to +20 degrees at the equator. The magnetic field on Mars is much weaker than that of the Earth, and the atmosphere is quite rarefied, which allows solar radiation to freely affect the surface. In this regard, if there is life on Mars, it is not on the surface.

When surveyed with the help of rovers, it was found that there are many mountains on Mars, as well as dried riverbeds and glaciers. The surface of the planet is covered with red sand. Iron oxide gives Mars its color.

1. Mars is located on the fourth orbit from the Sun;
2. The Red Planet hosts the tallest volcano in the solar system;
   
3. Of the 40 exploration missions sent to Mars, only 18 were successful;
4. Mars has the largest dust storms in the solar system;
5. In 30-50 million years, a system of rings will be located around Mars, like that of Saturn;
6. Fragments of Mars have been found on Earth;
7. The sun from the surface of Mars looks half as large as from the surface of the Earth;
   
8. Mars is the only planet in the solar system that has polar ice caps;
9. Two natural satellites revolve around Mars - Deimos and Phobos;
10. Mars has no magnetic field;

Jupiter

This planet is the largest in the solar system and has a diameter of 139,822 km, which is 19 times larger than the earth. A day on Jupiter lasts 10 hours, and a year is approximately 12 Earth years. Jupiter is mainly composed of xenon, argon, and krypton. If it were 60 times larger, it could become a star due to a spontaneous thermonuclear reaction.

The average temperature on the planet is -150 degrees Celsius. The atmosphere is made up of hydrogen and helium. There is no oxygen or water on its surface. There is an assumption that there is ice in the atmosphere of Jupiter.

1. Jupiter is located in the fifth orbit from the Sun;
2. In the earth's sky, Jupiter is the fourth brightest object, after the Sun, Moon and Venus;
   
3. Jupiter has the shortest day of all the planets in the solar system;
4. In Jupiter's atmosphere, one of the longest and most powerful storms in the solar system, better known as the Great Red Spot, rages;
5. Jupiter's moon, Ganymede, is the largest moon in the solar system;
6. Around Jupiter is a thin system of rings;
7. Jupiter was visited by 8 research vehicles;
   
8. Jupiter has a strong magnetic field;
   
9. If Jupiter were 80 times more massive, it would become a star;
10. There are 67 natural satellites revolving around Jupiter. This is the largest figure in the solar system;

Saturn

This planet is the second largest in the solar system. Its diameter is 116,464 km. It is most similar in composition to the Sun. A year on this planet lasts quite a long time, almost 30 Earth years, and a day is 10.5 hours. The average surface temperature is -180 degrees.

Its atmosphere consists mainly of hydrogen and a small amount of helium. Thunderstorms and auroras often occur in its upper layers.

1. Saturn is the sixth planet from the Sun;
2. In the atmosphere of Saturn, the most strong winds in the solar system;
   
3. Saturn is one of the least dense planets in the solar system;
   
4. Around the planet is the largest ring system in the solar system;
5. One day on the planet lasts almost one Earth year and is equal to 378 Earth days;
6. Saturn was visited by 4 research spacecraft;
7. Saturn together with Jupiter make up approximately 92% of the entire planetary mass of the solar system;
8. One year on the planet lasts 29.5 Earth years;
9. There are 62 known natural satellites revolving around the planet;
10. Currently, the automatic interplanetary station Cassini is engaged in the study of Saturn and its rings;

Uranus

Uranus, computer artwork.

Uranus is the third largest planet in the solar system and the seventh from the Sun. It has a diameter of 50,724 km. It is also called the "ice planet", as the temperature on its surface is -224 degrees. A day on Uranus lasts 17 hours, and a year is 84 Earth years. At the same time, summer lasts as long as winter - 42 years. Such a natural phenomenon due to the fact that the axis of that planet is located at an angle of 90 degrees to the orbit and it turns out that Uranus, as it were, "lies on its side."

1. Uranus is located in the seventh orbit from the Sun;
2. The first to know about the existence of Uranus was William Herschel in 1781;
   
3. Only one spacecraft has visited Uranus, Voyager 2 in 1982;
4. Uranus is the coldest planet in the solar system;
5. The equatorial plane of Uranus is inclined to the plane of its orbit almost at a right angle - that is, the planet rotates retrograde, "lying on its side slightly upside down";
6. The moons of Uranus bear names taken from the works of William Shakespeare and Alexander Pope, not from Greek or Roman mythology;
7. A day on Uranus lasts about 17 Earth hours;
8. There are 13 known rings around Uranus;
9. One year on Uranus lasts 84 Earth years;
10. There are 27 known natural satellites revolving around Uranus;

Neptune

Neptune is the eighth planet from the Sun. In its composition and size, it is similar to its neighbor Uranus. The diameter of this planet is 49,244 km. A day on Neptune lasts 16 hours, and a year is equal to 164 Earth years. Neptune belongs to the ice giants and for a long time it was believed that no weather events occur on its icy surface. However, it has recently been found that Neptune has raging eddies and wind speeds the highest of the planets in the solar system. It reaches 700 km / h.

Neptune has 14 moons, the most famous of which is Triton. It is known that it has its own atmosphere.

Neptune also has rings. This planet has 6.

1. Neptune is the most distant planet in the solar system and occupies the eighth orbit from the Sun;
2. Mathematicians were the first to know about the existence of Neptune;
   
3. There are 14 moons circling Neptune;
4. The orbit of Nepputna is removed from the Sun by an average of 30 AU;
5. One day on Neptune lasts 16 Earth hours;
6. Neptune has only been visited by one spacecraft, Voyager 2;
7. Around Neptune there is a system of rings;
8. Neptune has the second highest gravity after Jupiter;
9. One year on Neptune lasts 164 Earth years;
10. The atmosphere on Neptune is extremely active;

1. Jupiter is considered the largest planet in the solar system.
2. There are 5 dwarf planets in the solar system, one of which was reclassified as Pluto.
3. There are very few asteroids in the solar system.
4. Venus is the hottest planet in the solar system.
5. About 99% of the space (by volume) is occupied by the Sun in the solar system.
6. One of the most beautiful and original places in the solar system is the satellite of Saturn. There you can see a huge concentration of ethane and liquid methane.
7. Our solar system has a tail that resembles a four-leaf clover.
8. The sun follows a continuous 11-year cycle.
9. There are 8 planets in the solar system.
10. The solar system is fully formed thanks to a large gas and dust cloud.
11. Spacecraft flew to all the planets of the solar system.
12. Venus is the only planet in the solar system that rotates counterclockwise on its axis.
13. Uranus has 27 moons.
14. The largest mountain is on Mars.
15. A huge mass of objects in the solar system fell on the Sun.
16. The solar system is part of the Milky Way galaxy.
17. The sun is the central object of the solar system.
18. The solar system is often divided into regions.
19. The sun is a key component of the solar system.
20. The solar system was formed about 4.5 billion years ago.
21. Pluto is the most distant planet in the solar system.
22. Two regions in the solar system are filled with small bodies.
23. The solar system is built contrary to all the laws of the universe.
24. If we compare the solar system and space, then it is just a grain of sand in it.
25. Over the past few centuries, the solar system has lost 2 planets: Vulcan and Pluto.
26. Researchers claim that the solar system was created artificially.
27. The only satellite in the solar system that has a dense atmosphere and whose surface cannot be seen due to cloud cover is Titan.
28. The region of the solar system beyond the orbit of Neptune is called the Kuiper Belt.
29. The Oort cloud is a region of the solar system that serves as the source of a comet and a long period of revolution.
30. Every object in the solar system is held there by gravity.
31. The leading theory of the solar system proposes the emergence of planets and satellites from a huge cloud.
32. The solar system is considered the most secret particle of the Universe.
33. There is a huge asteroid belt in the solar system.
34. On Mars, you can see the eruption of the largest volcano in the solar system, which is called Olympus.
35. Pluto is considered to be the outskirts of the solar system.
36. Jupiter has a large ocean liquid water.
37. The Moon is the largest satellite in the solar system.
38. by the most big asteroid The solar system is Pallas.
39. The most bright planet Solar system - Venus.
40. The majority of the solar system is made up of hydrogen.
41. Earth is an equal member of the solar system.
42. The sun heats up slowly.
43. Oddly enough, the largest reserves of water in the solar system are in the sun.
44. The plane of the equator of each planet in the solar system diverges from the plane of the orbit.
45. The satellite of Mars with the name Phobos is an anomaly of the solar system.
46. The solar system can amaze with its diversity and scale.
47. The planets of the solar system are influenced by the sun.
48. The outer shell of the solar system is considered the haven of satellites and gas giants.
49. A huge number of planetary satellites of the solar system are dead.
50. The largest asteroid, with a diameter of 950 km, is called Ceres.

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, which has long been considered the ninth planet of the solar system, has a prehistory.

Before the advent of telescopes, mankind knew five celestial bodies called planets (translated from Greek - “wanderers”): Mercury, Venus, Mars, Jupiter, Saturn. For four centuries, two more large planets were discovered: 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 ruled that the name of any new planet must correspond to 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 a large 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! A new mystery has inspired astronomers to search for a trans-Neptunian object, which has become 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 °. Such an unusual property made it possible to speculate on whether Pluto is the home planet of the solar system or whether it is accidentally attracted by the gravity of the Sun (for example, Ivan Efremov considers this hypothesis 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, Pluto's rarefied atmosphere, consisting of methane and nitrogen, last years noticeably "swollen", 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 "demotion", 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, the total number of registered objects of the Edgeworth-Kuiper belt exceeded one 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 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 at 1,170 km). 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! On November 14, 2003, Brown's team discovers the trans-Neptunian object 2003 VB12, which is named Sedna, after the Eskimo goddess of the sea, who lives at the bottom of the 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 god-creator of mankind in the mythology of the Rapanui people, the inhabitants of Easter Island). The colleagues' patience snapped, and they gathered for a 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 with the fact that the discussion 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 to the decision of the International Astronomical Union in different ways: someone did not attach importance, but someone was convinced that scientists were fooling around. AT English language the verb "to pluto" ("to plutonize") 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 ever "brothers in mind", guided by the "Pioneers" scheme, want to find us, they highly likely will pass by, entangled 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)

The solar system is a planetary system that includes the central star - the Sun - and all the natural objects of space revolving around it. It was formed by gravitational compression of a gas and dust cloud about 4.57 billion years ago. We will find out which planets are part of the solar system, how they are located in relation to the Sun and their brief description.

Brief information about the planets of the solar system

The number of planets in the solar system is 8, and they are classified in order of distance from the Sun:

• Inner planets or terrestrial planets- Mercury, Venus, Earth and Mars. They consist mainly of silicates and metals.
• outer planets- Jupiter, Saturn, Uranus and Neptune are the so-called gas giants. They are much more massive than the terrestrial planets. The largest planets in the solar system, Jupiter and Saturn, are composed mainly of hydrogen and helium; smaller gas giants, Uranus and Neptune, in addition to hydrogen and helium, contain methane and carbon monoxide in their atmospheres.

Rice. 1. Planets of the solar system.

The list of planets in the solar system in order from the sun is as follows: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. By listing the planets from largest to smallest, this order changes. The largest planet is Jupiter, followed by Saturn, Uranus, Neptune, Earth, Venus, Mars and finally Mercury.

All planets revolve around the Sun in the same direction as the Sun's rotation (counterclockwise as viewed from the north pole of the Sun).

Mercury has the highest angular velocity - it manages to make a complete revolution around the Sun in just 88 Earth days. And for the most distant planet - Neptune - the period of revolution is 165 Earth years.

Most of the planets rotate around their axis in the same direction as they revolve around the sun. The exceptions are Venus and Uranus, and Uranus rotates almost "lying on its side" (axis tilt is about 90 degrees).

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Table. The sequence of the planets in the solar system and their features.

Terrestrial planets (inner planets)

The four planets closest to the Sun consist mainly of heavy elements, have a small number of satellites, and have no rings. They are largely composed of refractory minerals such as silicates that form their mantle and crust, and metals such as iron and nickel that form their core. Three of these planets - Venus, Earth and Mars - have an atmosphere.

• Mercury- is the closest planet to the Sun and the smallest planet in the system. The planet has no satellites.
• Venus- is close in size to the Earth and, like the Earth, has a thick silicate shell around the iron core and atmosphere (because of this, Venus is often called the "sister" of the Earth). However, the amount of water on Venus is much less than on Earth, and its atmosphere is 90 times denser. Venus has no satellites.

Venus is the hottest planet in our system, with surface temperatures exceeding 400 degrees Celsius. The most likely reason for such a high temperature is the greenhouse effect due to the dense atmosphere rich in carbon dioxide.

Rice. 2. Venus is the hottest planet in the solar system

• Earth- is the largest and densest of the terrestrial planets. The question of whether life exists anywhere other than Earth remains open. Among the terrestrial planets, the Earth is unique (primarily due to the hydrosphere). Earth's atmosphere is radically different from the atmospheres of other planets - it contains free oxygen. The Earth has one natural satellite - the Moon, the only large satellite of the planets of the terrestrial group of the solar system.
• Mars smaller than Earth and Venus. It has an atmosphere composed mainly of carbon dioxide. On its surface there are volcanoes, the largest of which, Olympus, exceeds the size of all terrestrial volcanoes, reaching a height of 21.2 km.

Outer region of the solar system

The outer region of the solar system is the location of the gas giants and their satellites.

• Jupiter- has a mass of 318 times more than the earth, and 2.5 times more massive than all the other planets combined. It consists mainly of hydrogen and helium. Jupiter has 67 moons.
• Saturn- known for its extensive ring system, it is the least dense planet in the solar system (its average density is less than that of water). Saturn has 62 moons.

Rice. 3. Planet Saturn.

• Uranus- the seventh planet from the Sun is the lightest of the giant planets. What makes it unique among other planets is that it rotates "lying on its side": the inclination of its axis of rotation to the plane of the ecliptic is approximately 98 degrees. Uranus has 27 moons.
• Neptune is the last planet in the solar system. Although slightly smaller than Uranus, it is more massive and therefore denser. Neptune has 14 known moons.

What have we learned?

One of the interesting topics of astronomy is the structure of the solar system. We learned what names of the planets of the solar system are, in what order they are located in relation to the Sun, what are their distinctive features and brief characteristics. This information is so interesting and informative that it will be useful even for children in grade 4.

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Pluto is one of the least explored objects in the solar system. Due to its great distance from the Earth, it is difficult to observe with telescopes. Its appearance is more like a small star than a planet. But until 2006, it was he who was considered the ninth planet of the solar system known to us. Why was Pluto excluded from the list of planets, what led to this? Let's consider everything in order.

Unknown to science "Planet X"

At the end of the 19th century, astronomers suggested that there must be another planet in our solar system. The assumptions were based on scientific data. The fact is that, while observing Uranus, scientists discovered a strong influence of foreign bodies on its orbit. So, after some time, Neptune was discovered, but the influence was much stronger, and the search for another planet began. It was called "Planet X". The search continued until 1930 and was crowned with success - Pluto was discovered.

Pluto's movement was noticed on photographic plates taken over the course of two weeks. Observations and confirmation of the existence of an object beyond the known limits of the galaxy of another planet took more than a year. Clyde Tombaugh, a young astronomer at the Lowell Observatory that initiated the research, announced the discovery to the world in March 1930. So, the ninth planet appeared in our solar system for 76 years. Why was Pluto excluded from the solar system? What was wrong with this mysterious planet?

New discoveries

At one time, Pluto, classified as a planet, was considered the last of the objects in the solar system. According to preliminary data, its mass was considered equal to the mass of our Earth. But the development of astronomy constantly changed this indicator. Today, Pluto's mass is less than 0.24% and its diameter is less than 2,400 km. These indicators were one of the reasons why Pluto was excluded from the list of planets. It is more suitable for a dwarf than for a full-fledged planet in the solar system.

It also has many of its own features that are not inherent in ordinary planets of the solar system. The orbit, its small satellites and atmosphere are unique in themselves.

unusual orbit

Orbits habitual for eight planets of the solar system are almost round, having a slight inclination along the ecliptic. But Pluto's orbit is a highly elongated ellipse and has an inclination angle of more than 17 degrees. If you imagine that eight planets will rotate around the Sun uniformly, and Pluto will cross the orbit of Neptune because of its angle of inclination.

In view of such an orbit, it makes a revolution around the Sun in 248 Earth years. And the temperature on the planet does not rise above minus 240 degrees. Interestingly, Pluto rotates in the opposite direction from our Earth, like Venus and Uranus. This unusual orbit for the planet was another reason why Pluto was excluded from the list of planets.

satellites

Today five Charons, Nikta, Hydra, Cerberus and Styx are known. All of them, except for Charon, are very small, and their orbits are too close to the planet. This is another one of the differences from the officially recognized planets.

In addition, Charon, discovered in 1978, is half the size of Pluto itself. But for a satellite it is too big. Interestingly, the center of gravity is outside of Pluto, and therefore it seems to swing from side to side. For these reasons, some scientists consider this object a double planet. And this also serves as an answer to the question of why Pluto was excluded from the list of planets.

Atmosphere

It is very difficult to study an object located at an almost inaccessible distance. It is assumed that Pluto consists of rocks and ice. The atmosphere on it was discovered in 1985. It consists mainly of nitrogen, methane and carbon monoxide. Its presence was able to determine when studying the planet, when it closed the star. Objects without an atmosphere cover the stars abruptly, while objects with an atmosphere close gradually.

Due to the very low temperature and elliptical orbit, melting ice produces an anti-greenhouse effect, which leads to an even greater decrease in temperature on the planet. After research conducted in 2015, scientists concluded that Atmosphere pressure depends on the planet's approach to the sun.

The latest technology

The creation of new powerful telescopes marked the beginning of further discoveries beyond the known planets. So, over time, those within the orbit of Pluto were discovered. In the middle of the last century, this ring was called the Kuiper belt. To date, hundreds of bodies are known with a diameter of at least 100 km and a composition similar to Pluto. The found belt turned out to be main reason why Pluto was excluded from the planets.

The creation of the Hubble Space Telescope made it possible to study outer space in more detail, and especially distant galactic objects. As a result, an object called Eris was discovered, which turned out to be farther than Pluto, and over time, two more celestial bodies that were similar in diameter and mass to it.

The AMS New Horizons spacecraft, sent to explore Pluto in 2006, confirmed many of the scientific data. Scientists have a question about what to do with open objects. Are they classified as planets? And then in the solar system there will be not 9, but 12 planets, or the exclusion of Pluto from the list of planets will solve this issue.

Status review

When was Pluto removed from the list of planets? On August 25, 2006, the participants of the Congress of the International Astronomical Union, consisting of 2.5 thousand people, made a sensational decision - to exclude Pluto from the list of planets in the solar system. This meant that it was necessary to revise and rewrite many textbooks, as well as star charts and scientific works in this region.

Why was such a decision made? Scientists have had to rethink the criteria by which planets are classified. A long debate led to the conclusion that the planet must meet all the parameters.

First, the object must revolve around the Sun in its orbit. Pluto suits this parameter. Although its orbit is highly elongated, it revolves around the Sun.

Secondly, it should not be a satellite of another planet. This point also corresponds to Pluto. At one time it was believed that he was, but this assumption was discarded with the advent of new discoveries, and especially his own satellites.

The third point is to have enough mass to acquire a spherical shape. Pluto, although small in mass, is round, and this is confirmed by photographs.

And finally, the fourth requirement is to have a strong one to clear your orbit from others. For this one point, Pluto does not fit the role of a planet. It is located in the Kuiper belt and is not the largest object in it. Its mass is not enough to clear a path for itself in orbit.

Now it is clear why Pluto was excluded from the list of planets. But where do we list such objects? For such bodies, the definition of "dwarf planets" was introduced. They began to include all objects that do not correspond to the last paragraph. So Pluto is still a planet, albeit a dwarf one.

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Why is Pluto not considered a planet?: discovery of Pluto with photo, finding objects in the Kuiper belt, new IAU classification and criteria, dwarf planet.

In 1930, Clyde Tomb managed to find Pluto, which became the 9th planet of our system. Scientist whole year photographed the sky and studied the pictures. On one pair, he noticed a shifting object. The name came from an 11-year-old schoolgirl in honor of the Roman deity who rules the other world.

Why Pluto is no longer a planet

Little was known about the mass until the discovery of a large satellite of Charon nearby (1978). As a result, we managed to come to the size (2400 km). Despite its tinyness, it was considered last object and a planet beyond the orbit of Neptune.

But terrestrial instruments improved, we managed to launch devices into space, and we were able to expand the boundaries of observation. Soon they found the rest of the moons of Pluto, and then the Kuiper belt, distant from Neptune at 55 AU.

At least 70,000 icy bodies live in this area, which are the same as Pluto in composition and extend 100 km or more in width. With their discovery, new rules appeared and Pluto did not pass the test for planetary nature.

The problem is the following. Each time there were more and more objects that exceeded the parameters of Pluto.

And in 2005, Michael Brown finds Eris, located further, but larger than Pluto (2600 km) and larger in mass. The concept of 9 planets started to crumble. What is Eris? Also a planet or just an object from the Kuiper belt? And then what is Pluto? A dispute ensued between scientists, and in 2006 a meeting of the IAU was convened in Prague.

It was important to derive a clear definition of the concept of "planet". If they voted for one version, then the number solar planets increased to 12, but as a result, we reduced it to 8. What is Pluto?

Now it is a class of dwarf planets.

To become a planet, the body must:

• make revolutions around the sun;
• have sufficient massiveness to become spherical;
• clear the surroundings of objects;

Pluto failed to fulfill the last condition. Now all bodies that meet the first two but fail on the third requirement are called dwarf planets.

But let's not forget that large objects are hiding in the Kuiper belt and one of them can become the 9th planet. With the downgrade, Pluto has not lost its popularity and scientific interest. Therefore, in 2015, the New Horizons mission was sent to him. Let's not forget that there are still scientists who do not recognize the decision of the IAU.