Pluto is not the only body in the outskirts of our system. The planet is located at the beginning of Kayperoviya belt – a region on the edge of the solar system that extends beyond the atmosphere of the gas giant Neptune. It is similar to the asteroid belt, but is much greater than that between Mars and Saturn, with a width of about 3 billion. Km.
Over the past two decades, fierce debate about whether Pluto should be considered the ninth planet in the solar system, or to create a new category of celestial bodies to be entered in it. The reason is that in the 90s of last century in Kayperoviya belt were discovered cosmic bodies of similar size. This leads to the creation of a precise definition of whether an object is a planet or not. According to the International Astronomical Union (IAU) it must meet three criteria – the object must be in orbit with the sun, be massive enough that its own gravity to create enabling hydrostatic equilibrium (ie have a relatively symmetrical spherical shape) and be dominant cosmic body in the area. Pluto fails to meet the last criterion for the presence of many other bodies that collectively have a large table. Therefore, the ninth planet under IAU’s dwarf planet: thesis, opposed by much of the scientific community, including one of the leaders of the mission “New Horizons”, Adam Stern. According to critics, if applied this rule, Earth, Mars and Jupiter will also be planets because the asteroid belt between the last two.