Planets are celestial bodies that have the following characteristics:
* Orbiting around the star or the remnants of stars;
* Have enough mass to have its own gravity to overcome rigid body so that the pressure of a celestial body that has the form of a hydrostatic equilibrium (nearly round shape);
* Not too big that can cause thermonuclear fusion of deuterium in its core, and,
* Has been "clean environment" (clearing the neighborhood; empty orbit for unoccupied space objects large enough other than the satellite itself) in the area around its orbit
* More than 800 km in diameter
Based on the above definition, then the system there are eight planets of the Solar System. Until August 24, 2006, before the International Astronomical Union (IAU = International Astronomical Union) announced changes to the definition of "planet" so that as mentioned above, there are nine planets, including Pluto, even celestial bodies found recently also could be considered as new planets, such as : Ceres, Sedna, Orcus, Xena, Quaoar, UB 313. Pluto, Ceres and UB 313 is now changing its status to "dwarf planet / dwarf."
Planet taken from the Greek word meaning Star Asteres Planetai wanderer. So named because unlike ordinary stars, planets from time to time be seen wandering (move) from one constellation to another constellation. This displacement (at present) can be understood because the planets circulating around the sun. But in the days of ancient Greece who are not familiar with the concept of a heliocentric, the planet is considered as a representation of god in the sky. At that time the meaning of the planets are seven celestial bodies: the Sun, Moon, Mercury, Venus, Mars, Jupiter and Saturn. Modern astronomy to remove the Sun and Moon from the list because it does not fit the current definition. Previously, the planets in the solar system there are 9, namely Mercury, Venus, Earth, Mars, Jupiter / Jupiter, Saturn, Uranus, Neptune, and Pluto. However, on 26 August 2006, the scientists agreed to remove Pluto from the list of planets, so the number of planets in the solar system to only 8.
* Orbiting around the star or the remnants of stars;
* Have enough mass to have its own gravity to overcome rigid body so that the pressure of a celestial body that has the form of a hydrostatic equilibrium (nearly round shape);
* Not too big that can cause thermonuclear fusion of deuterium in its core, and,
* Has been "clean environment" (clearing the neighborhood; empty orbit for unoccupied space objects large enough other than the satellite itself) in the area around its orbit
* More than 800 km in diameter
Based on the above definition, then the system there are eight planets of the Solar System. Until August 24, 2006, before the International Astronomical Union (IAU = International Astronomical Union) announced changes to the definition of "planet" so that as mentioned above, there are nine planets, including Pluto, even celestial bodies found recently also could be considered as new planets, such as : Ceres, Sedna, Orcus, Xena, Quaoar, UB 313. Pluto, Ceres and UB 313 is now changing its status to "dwarf planet / dwarf."
Planet taken from the Greek word meaning Star Asteres Planetai wanderer. So named because unlike ordinary stars, planets from time to time be seen wandering (move) from one constellation to another constellation. This displacement (at present) can be understood because the planets circulating around the sun. But in the days of ancient Greece who are not familiar with the concept of a heliocentric, the planet is considered as a representation of god in the sky. At that time the meaning of the planets are seven celestial bodies: the Sun, Moon, Mercury, Venus, Mars, Jupiter and Saturn. Modern astronomy to remove the Sun and Moon from the list because it does not fit the current definition. Previously, the planets in the solar system there are 9, namely Mercury, Venus, Earth, Mars, Jupiter / Jupiter, Saturn, Uranus, Neptune, and Pluto. However, on 26 August 2006, the scientists agreed to remove Pluto from the list of planets, so the number of planets in the solar system to only 8.