<Tr> <Td> "</Td> <Td> (1) A planet is a celestial body that (a) is by far the largest object in its local population (1), (b) has sufficient mass for its self - gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape (2), (c) does not produce energy by any nuclear fusion mechanism (3). <P> (2) According to point (1) the eight classical planets discovered before 1900, which move in nearly circular orbits close to the ecliptic plane are the only planets of the Solar System . All the other objects in orbit around the Sun are smaller than Mercury . We recognize that there are objects that fulfill the criteria (b) and (c) but not criterion (a). Those objects are defined as "dwarf" planets . Ceres as well as Pluto and several other large Trans - Neptunian objects belong to this category . In contrast to the planets, these objects typically have highly inclined orbits and / or large eccentricities . </P> <P> (3) All the other natural objects orbiting the Sun that do not fulfill any of the previous criteria shall be referred to collectively as "Small Solar System Bodies". (4) </P> <Dl> <Dt> Definitions and clarifications </Dt> <Dd> </Dd> </Dl> <Ol> <Li> The local population is the collection of objects that cross or closely approach the orbit of the body in consideration . </Li> <Li> This generally applies to objects with sizes above several hundred kilometers, depending on the material strength . </Li> <Li> This criterion allows the distinction between gas giant planets and brown dwarfs or stars . </Li> <Li> This class currently includes most of the Solar System asteroids, Near - Earth objects (NEOs), Mars -, Jupiter - and Neptune - Trojan asteroids, most Centaurs, most Trans - Neptunian Objects (TNOs), and comets . </Li> </Ol> </Td> <Td>" </Td> </Tr> <P> (2) According to point (1) the eight classical planets discovered before 1900, which move in nearly circular orbits close to the ecliptic plane are the only planets of the Solar System . All the other objects in orbit around the Sun are smaller than Mercury . We recognize that there are objects that fulfill the criteria (b) and (c) but not criterion (a). Those objects are defined as "dwarf" planets . Ceres as well as Pluto and several other large Trans - Neptunian objects belong to this category . In contrast to the planets, these objects typically have highly inclined orbits and / or large eccentricities . </P> <P> (3) All the other natural objects orbiting the Sun that do not fulfill any of the previous criteria shall be referred to collectively as "Small Solar System Bodies". (4) </P> <Dl> <Dt> Definitions and clarifications </Dt> <Dd> </Dd> </Dl>

In the exoplanet classification system a planet like the earth would be classified as a