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ก็อย่างข้างบนว่า
http://en.wikipedia.org/wiki/Pluto
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IAU decision and the "Great Pluto War"
Main article: 2006 redefinition of planet
The debate came to a head in 2006 with an IAU resolution that created an official definition for the term "planet". According to this resolution, there are three main conditions for an object to be considered a 'planet':
1 ต้องโคจรรอบอาทิตย์
2 ต้องมีมวลเป็นทรงกลมจากแรงดึงดูดมันเอง
3 ต้องมีวงโคจรแยกชัดจากดาวข้างๆ
The object must be in orbit around the Sun.
The object must be massive enough to be a sphere by its own gravitational force. More specifically, its own gravity should pull it into a shape of hydrostatic equilibrium.
It must have cleared the neighbourhood around its orbit.[89]
พลูโตสอบตกข้อ3 IAUแก้ปัญหายกพลูโตเป็นดาวเคราะห์แคระ
Pluto fails to meet the third condition.[90] The IAU further resolved that Pluto be classified in the simultaneously created dwarf planet category, and that it act as prototype for a yet-to-be-named category of trans-Neptunian objects, in which it would be separately, but concurrently, classified.
There has been resistance amongst the astronomical community towards the reclassification,[91] dubbed the "Great Pluto War" by some astronomers.[92][93] Alan Stern, principal investigator with NASA's "New Horizons" mission to Pluto, has publicly derided the IAU resolution, stating that "the definition stinks, for technical reasons."[94] Stern's current contention is that by the terms of the new definition Earth, Mars, Jupiter and Neptune, all of which share their orbits with asteroids would be excluded.[95] However, his own published writing has supported the new list of planets, as "our solar system clearly contains" eight planets that have cleared their neighbourhoods.[96] Marc W. Buie of the Lowell observatory has voiced his opinion on the new definition on his website and is one of the petitioners against the definition.[97] Others have supported the IAU. Mike Brown, the astronomer who discovered Eris, said "through this whole crazy circus-like procedure, somehow the right answer was stumbled on. Its been a long time coming. Science is self-correcting eventually, even when strong emotions are involved."[98]
Among the general public, reception is mixed amidst widespread media coverage. Some have accepted the reclassification, while some are seeking to overturn the decision, with online petitions urging the IAU to consider reinstatement. A resolution introduced by some members of the California state assembly light-heartedly denounces the IAU for "scientific heresy," among other crimes.[99] The U.S. state of New Mexico's House of Representatives passed a resolution declaring that, in honour of Tombaugh, a longtime resident of that state, Pluto will always be considered a planet while in New Mexican skies, with March 13 being known as "Pluto Planet Day".[100] Others reject the change for sentimental reasons, citing that they have always known Pluto as a planet and will continue to do so regardless of the IAU decision.[101]
The verb "pluto" (preterite and past participle: "plutoed") was coined in the aftermath of the decision. In January 2007, the American Dialect Society chose "plutoed" as its 2006 Word of the Year, defining "to pluto" as "to demote or devalue someone or something", an example being "as happened to the former planet Pluto when the General Assembly of the International Astronomical Union decided Pluto no longer met its definition of a planet."[102]
รูปวงโคจร
http://www.stargazer.htmlplanet.com/plutos_orbit_image.html
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