Pluto is a planet named after a mythological deity. For a long time it was the last, the ninth planet of the Solar system. Pluto was considered not only the smallest, but also the coldest and little studied. But in 2006 with the purpose of its more detailed research the device which in 2015 reached Pluto was started. His mission will be completed in 2026. The size of Pluto is so small that since 2006 it has ceased to be considered a planet! However, many call this decision far-fetched and unreasonable. Perhaps soon Pluto will again take its former place among the cosmic bodies of our Solar system. Back in the 19th century, scientists were convinced that behind Uranium is another planet. The power of the telescopes of that time did not allow them to detect it. Why is Neptune so eagerly searching for? The fact is that the distortions of the orbit of Uranus and Neptune could be explained only by the presence of another planet behind it, which has an impact on it. As if “pulling” on themselves. And in 1930, Neptune was finally discovered. However, it turned out to be quite small in order to cause such disturbances of Uranus and Neptune. In addition, its axis is as inclined as the axes of Uranus and Neptune. That is, the influence of an unknown celestial body affects it. Scientists are still looking for a mysterious planet Nibiru, wandering through our Solar system. Some believe that it can soon become the cause of the ice age on Earth. However, its existence is still not confirmed. Although its description, suggest researchers, there is in ancient Sumerian texts. But even if the killer planet does exist, we don’t have to worry about the end of the world. The fact is that the approach of the celestial body we will see 100 years before its alleged collision with the Earth. And we will return to Pluto, opened in 1930 in Arizona by Clyde tombo. The search for the so-called planet-X was conducted since 1905, but only a team of American scientists managed to make this discovery. The question arose, what name to give the discovered planet. And to call her Pluto suggested eleven-year-old schoolgirl Venice Bernie. Her grandfather learned about the difficulties in finding a name and asked what would be the name of the planet gave granddaughter. And Venice very quickly gave a reasonable answer. The girl was interested in astronomy and mythology. Pluto – Roman version of the name of the God of the underworld Hades. Venice explained its logic very simply – this name is the best in harmony with the silent and cold cosmic body. And it was the discovery of its largest satellite that helped to establish the mass of Pluto. Called him Charon, in honor of otherworldly beings, carrying the souls of the dead to the underworld. The mass of Charon was even then known fairly accurately – 0,0021 the mass of the Earth. This made it possible to know the approximate mass and diameter of Plato, using Kepler’s formulation. In the presence of two objects of different masses, it allows us to conclude about their size. But these are only approximate figures. The exact size of Pluto became known only in 2015. Thus, its diameter is 2370 km (or 1500 miles). And the mass of the planet Pluto is 1.3 × 1022 kg, and the volume is 6.39·109 km3. Length – 2370. For comparison, the diameter of Eris, the largest dwarf planet in our Solar system, is 1600 miles. Therefore, it is not surprising that Pluto in 2006 decided to assign the status of a dwarf planet. That is, it is the tenth heaviest object in the Solar system and the second – among the dwarf planets. Mercury is the closest planet to the Sun. He is the complete opposite of the ice baby. When comparing the size of mercury and Pluto, the latter loses. Because the diameter closest to the Sun planet is 4879 km and a difference in density of the two “kids”. The composition of mercury is mainly represented by stone and metal. Its density is 5.427 g/cm3. A Pluto at a density of 2 g/cm3 contains mainly ice and stone. It is inferior to mercury in gravity. If you could visit a dwarf planet, you would break away from its surface at every step. When in 2006 Pluto ceased to be ranked as a full-fledged planet, the title of space baby again went to mercury. And the title of the coldest got the Neptune. The dwarf planet is also smaller than the two largest satellites of our Solar system – Ganymede and Titan. These celestial bodies also vary in size. Our Moon is not the largest satellite in the Solar system. In fact, experts have not yet decided on the interpretation of the term “satellite”, perhaps once it will be called a planet. However, the size of Pluto, in comparison with the Moon, clearly lose – it is 6 times smaller than the earth’s satellite. Its size in kilometers – 3474. And the density is 60% of the earth and is second only to the satellite of Saturn IO among the celestial bodies of our Solar system. How much smaller is Pluto than Earth? A comparison of the size of Pluto and the Earth clearly shows how small it is. It turns out that inside our planet would fit 170 plutons. NASA even presented a graphic image where Neptune is located on the background of the Earth. It is impossible to explain better how different their masses are. Russia is the largest country on our planet. The surface area of 17 098 242 km2. And the surface area of Pluto is 16 650 000 km2. Comparison of the size of Pluto and Russia in the human understanding make the planet quite insignificant. Is Pluto a planet at all? Scientists believe that the planet can be considered a celestial body that has clean space. That is, the gravitational field of the planet must either absorb the nearest space objects or throw them out of the system. But the mass of Pluto is only 0.07 of the total mass of nearby objects. For comparison, the mass of our Earth is 1.7 million times greater than the mass of objects in its orbit. The reason to classify Pluto to the list of dwarf planets was another fact – in the Kuiper belt, where the space baby is localized, larger space objects were found. The final touch was the discovery of the dwarf planet Eris. Michael brown, who opened it, even wrote a book called “How I killed Pluto.” In fact, scientists, including Pluto to the nine planets of the Solar system, understood – it’s a matter of time. Once space goes explored further than Pluto – and there are bound to be larger cosmic bodies. And to call Pluto a planet would be incorrect. Formally, Pluto is called a dwarf planet. But in fact, full-fledged planets do not fall under this classification. This term was introduced in the same year 2006. The dwarf list includes Ceres (the largest asteroid in our Solar system), Eris, Haumea, Makemake and Pluto. In General, while the term dwarf planets is not clear all, as the exact definition of it has not yet come up.