The Solar System
Dwarf Planets
Pluto
Pluto is not a planet any more because it is so tiny. Next the IAU members gathered at the 2006 General Assembly agreed that a "planet" is defined as a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit. Pluto hasn't cleared the neighbourhood around its orbit that is why Pluto is not a planet.
Eris
Me and my dad thought this planet was called 2003 UB313 but it was really called Eris and me and my dad thought it was the 10th planet and pluto the 9th. The IAU changed the name and the name was changed on September the 13th.
Moon of Eris
Dysnomia
Before this moon was called S/2005 (2003 UB313) but now it's new name is called Dysnomia which is Eris's moon also it's name was changed on September the 13th 2006. Radius: 180km How Many km Across?: 360km and the moon is very small.
Ceres
2005 FY9
