Our universe is full of mysterious things. Some of the things are discovered but some of them are yet to be brought into the light. On 24 August 2004, International Astronomical Union defined about Planets, Dwarf planets.

Definition of Planets
International Astronomical Union stated that, Planet is a celestial body and is in the orbit around the Sun. Planet has sufficient mass for its self-gravity to overcome rigid body forces thus it is assumed that they posses hydrostatic equilibrium shape. And also that planet has cleared the neighborhood around its orbit.

Definition of Dwarf Planets
A dwarf planet is a outer space body and is in the orbit around the Sun. dwarf planet is assumed to have equilibrium shape and has sufficient mass for its self gravity to overcome rigid body forces. It is not a satellite. These have not cleared the neighborhood around its orbit.

• Ceres was discovered on January 1, 1801. Before reclassification as an asteroid, firstly it was classified as a planet for half a century.  Thereafter on September 13, 2006 it was named as Dwarf planet.
• Pluto  was discovered on February 18, 1930. It was regarded as a planet for 76 years and then after it was reclassified as a dwarf planet on August 24, 2006.
• Eris  was called as “tenth” planet member of solar system and was discovered on October 21, 2003. It was accepted as a dwarf planet on September 13, 2006.
• Makemake was discovered on March 31, 2005. It became member of dwarf planet family on July 11, 2008.
• Haumea was discovered on December 28, 2004.  It became dwarf planet on September 17, 2008.

Plutoids
The members of the IAU Committee on Small Body Nomenclature (CSBN) proposed the name “plutoid” which was accepted by the Board of Division III and by the IAU Working Group for Planetary System Nomenclature (WGPSN) and thereafter was approved by the IAU Executive Committee at its recent meeting in Oslo, Norway.

Plutoids are celestial bodies in orbit around the Sun and have sufficient mass for their self-gravity to overcome rigid body forces so that they assume a hydrostatic equilibrium and that have not cleared the neighborhood around their orbit. The three known plutoids are Pluto, Eris and MakeMake.

The number of known plutoids is likely to increase with the time. Various space organizations are working on discoveries of Dwarf Planets, Plutoids, and Planet.

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