IAU 2006 General Assembly: Result of the IAU Resolution votes24. August 2006, Prague ……six IAU Resolutions were also passed at the Closing Ceremony of the General Assembly:
5.Resolution 5A: "Definition of "planet" "
6.Resolution 6A: "Definition of Pluto-class objects"
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.
This means that the Solar System consists of eight "planets" Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. A new distinct class of objects called "dwarf planets" was also decided. It was agreed that "planets" and "dwarf planets" are two distinct classes of objects. The first members of the "dwarf planet" category are Ceres, Pluto and 2003 UB313 (temporary name). More "dwarf planets" are expected to be announced by the IAU in the coming months and years. Currently a dozen candidate "dwarf planets" are listed on IAU"s "dwarf planet" watchlist, which keeps changing as new objects are found and the physics of the existing candidates becomes better known.
The "dwarf planet" Pluto is recognised as an important proto-type of a new class of trans-Neptunian objects. The IAU will set up a process to name these objects.
據國際天文學聯合會網站訊息（IAU Website：News），在國際天文學聯合會（IAU）第26屆大會在2006年8月24日閉幕會透過的六項決議中，有兩項是關於行星的，即，決議5A：“‘行星’的定義”和決議6A：“冥（王星）族天體的定義”。
參加2006年大會的IAU成員們同意，一（個）“行星” 被定義為這樣的一（個）天體：（a）它處於環繞太陽的軌道上執行；（b）它有足夠大的質量，靠自身引力克服各種剛性的徹體力，以致呈現一種流體靜力平衡（幾乎圓球）形狀；（c）它清除了其軌道周圍的區域。
這意味著太陽系由八個行星——水星、金星、地球、火星、木星、土星、天王星、海王星（一些“矮行星”及“小天體”）組成。會議也決定了稱為“矮行星（dwarf planets）”一類新的、別具特性的天體。同意“行星”和“矮行星”是性質不同的兩類天體。“矮行星”首批成員有穀神星、冥王星和（暫時命名為）2003 UN313三個天體。預計在未來的數月和數年，國際天文學聯合會（IAU）將宣佈更多的“矮行星”。現在有一打的侯選“矮行星”列在.IAU的“矮行星”監視表上，當發現新天體和更瞭解已存侯選者的物理性質時，監視表會更改。
認識到“矮行星”冥王星作為新的一類“海（王星）外天體”或“冥族天體”的重要原型，國際天文學聯合會將建立一種程式來命名這些天體。
附件一：原文
IAU 2006 General Assembly: Result of the IAU Resolution votes24. August 2006, Prague ……six IAU Resolutions were also passed at the Closing Ceremony of the General Assembly:
5.Resolution 5A: "Definition of "planet" "
6.Resolution 6A: "Definition of Pluto-class objects"
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.
This means that the Solar System consists of eight "planets" Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. A new distinct class of objects called "dwarf planets" was also decided. It was agreed that "planets" and "dwarf planets" are two distinct classes of objects. The first members of the "dwarf planet" category are Ceres, Pluto and 2003 UB313 (temporary name). More "dwarf planets" are expected to be announced by the IAU in the coming months and years. Currently a dozen candidate "dwarf planets" are listed on IAU"s "dwarf planet" watchlist, which keeps changing as new objects are found and the physics of the existing candidates becomes better known.
The "dwarf planet" Pluto is recognised as an important proto-type of a new class of trans-Neptunian objects. The IAU will set up a process to name these objects.