Dwarf Planet in Our Solar System (in Hindi) || हमारे सौरमंडल का बौना ग्रह (हिंदी में)

Dwarf Planet in Our Solar System

A dwarf planet is a planetary-mass object that is neither a planet nor a natural satellite. That is, it is in direct orbit of the Sun, and is massive enough for its gravity to crush it into a hydrostatic equilibrium shape (usually a spheroid), but has not cleared the neighborhood of other material around its orbit.

Overview

The term dwarf planet has itself been somewhat controversial, as it implies that these bodies are planets, much as dwarf stars are stars. This is the conception of the Solar System that Stern promoted when he coined the phrase. The older word planetoid ("having the form of a planet") has no such connotation, and is also used by astronomers for bodies that fit the IAU definition.Brown states that planetoid is "a perfectly good word" that has been used for these bodies for years, and that the use of the term dwarf planet for a non-planet is "dumb", but that it was motivated by an attempt by the IAU division III plenary session to reinstate Pluto as a planet in a second resolution.Indeed, the draft of Resolution 5A had called these median bodies planetoids but the plenary session voted unanimously to change the name to dwarf planet.The second resolution, 5B, defined dwarf planets as a subtype of planet, as Stern had originally intended, distinguished from the other eight that were to be called "classical planets". Under this arrangement, the twelve planets of the rejected proposal were to be preserved in a distinction between eight classical planets and four dwarf planets. However, Resolution 5B was defeated in the same session that 5A was passed.Because of the semantic inconsistency of a dwarf planet not being a planet due to the failure of Resolution 5B, alternative terms such as nanoplanet and subplanet were discussed, but there was no consensus among the CSBN to change it.

In most languages equivalent terms have been created by translating dwarf planet more-or-less literally: French planète naine, Spanish planeta enano, German Zwergplanet, Russian karlikovaya planeta , Arabic kaukab qazm , Chinese ǎixíngxīng Korean waesohangseong. but Japanese and Latin are exceptions: In Japanese they are called junwakusei meaning "subplanets" or "almost-planets", and the modern Latin name, planetula (or planetion following the Greek), is a diminutive derivation of planeta, hence also meaning something less than a planet.

IAU Resolution 6a of 2006 recognizes Pluto as "the prototype of a new category of trans-Neptunian objects". The name and precise nature of this category were not specified but left for the IAU to establish at a later date; in the debate leading up to the resolution, the members of the category were variously referred to as plutons and plutonian objects but neither name was carried forward, perhaps due to objections from geologists that this would create confusion with their pluton.

On 11 June 2008, the IAU Executive Committee announced a name, plutoid, and a definition: all trans-Neptunian dwarf planets are plutoids. The authority of that initial announcement, however, has not been universally recognized: