Planetとは 意味・読み方・使い方

発音

• (Received Pronunciation, General American) IPA: /ˈplænɪt/
• (General Australian, weak vowel merger) IPA: /ˈplænət/
• • 韻: -ænɪt

名詞

planet (plural planets)

1. (now historical or astrology) Each of the seven major bodies which move relative to the fixed stars in the night sky—the Moon, Mercury, Venus, the Sun, Mars, Jupiter and Saturn. [from 14c.]
   • 1603, Michel de Montaigne, chapter 12, in John Florio, transl., The Essayes […], book II, London: […] Val[entine] Simmes for Edward Blount […], →OCLC, page 260:

     Be they not dreames of humane vanity, […] to make of our knowne earth a bright shining planet [translating astre]?

   • 1749, Henry Fielding, Tom Jones, Folio Society, published 1973, page 288:

     The moon […] began to rise from her bed, where she had slumbered away the day, in order to sit up all night. Jones had not travelled far before he paid his compliments to that beautiful planet, and, turning to his companion, asked him if he had ever beheld so delicious an evening?

   • 1971, Keith Thomas, Religion and the Decline of Magic, Folio Society, published 2012, page 361:

     Another of Boehme's followers, the Welshman Morgan Llwyd, also believed that the seven planets could be found within man.

2. (astronomy, historical) Any body that orbits the Sun, including the asteroids (as minor planets) and sometimes the moons of those bodies (as satellite planets)

   Synonyms: wandering star, wanderstar

   • 1640, John Wilkins, A Discovrse concerning a New Planet. Tending to prove, That 'tis probable our Earth is one of the Planets, title:

     A Discovrse concerning a New Planet. Tending to prove, That 'tis probable our Earth is one of the Planets

3. (astronomy, current) A body which is massive enough to be in hydrostatic equilibrium (generally resulting in being an ellipsoid) but not enough to attain nuclear fusion and, in IAU usage, which directly orbits a star (or multiple star) and dominates the region of its orbit; specifically, in the case of the Solar system, the eight major bodies of Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. [from 2006]

   Synonym: world

   Hypernym: planemo (in IAU usage)

   Hyponyms: binary planet, carbide planet, carbon planet, classical planet, diamond planet, double planet, dual planet, dwarf planet (in non-IAU usage), exoplanet, extrasolar planet, free-floating planet (in non-IAU usage), gas giant, giant planet, hycean planet, ice giant, inferior planet, inner planet, interstellar planet (in non-IAU usage), major planet, mesoplanet, minor planet (in non-IAU usage), outer planet, primary planet (in non-IAU usage), rogue planet (in non-IAU usage), satellite planet (in non-IAU usage), silicate planet, silicon planet, supergiant planet, superior planet, superplanet, terrestrial planet, water planet

   Coordinate terms: brown dwarf, sub-brown dwarf

   • 2006 December 22, Alok Jha, The Guardian:

     Their decision will force a rewrite of science textbooks because the solar system is now a place with eight planets and three newly defined "dwarf planets"—a new category of object that includes Pluto.

   • 2009 December 1, Keiichi Wada, Yusuke Tsukamoto, Eiichiro Kokubo, “Planet Formation around Supermassive Black Holes in the Active Galactic Nuclei”, in The Astrophysical Journal, volume 886, number 2, article 107:
   • 2023 November 29, Ashley Strickland, “Astronomers discover nearby six-planet solar system with ‘pristine configuration’”, in CNN‎:

     The closest planet takes just over nine Earth days to complete an orbit around the star, and the most distant takes about 55 days. All of the planets have quicker revolutions around their star than Mercury, which takes 88 days to complete one lap around the sun.

4. construed with the or this: The Earth.
   • 1907 August, Robert W[illiam] Chambers, chapter VIII, in The Younger Set, New York, N.Y.: D. Appleton & Company, →OCLC:

     "My tastes," he said, still smiling, "incline me to the garishly sunlit side of this planet." And, to tease her and arouse her to combat: "I prefer a farandole to a nocturne; I'd rather have a painting than an etching; Mr. Whistler bores me with his monochromatic mud; I don't like dull colours, dull sounds, dull intellects; […]."

   • 2013 June 7, David Simpson, “Fantasy of navigation”, in The Guardian Weekly, volume 188, number 26, page 36:

     It is tempting to speculate about the incentives or compulsions that might explain why anyone would take to the skies in [the] basket [of a balloon]: […]; perhaps to moralise on the oneness or fragility of the planet, or to see humanity for the small and circumscribed thing that it is; […].

使用する際の注意点

• The term planet originally meant any star which wandered across the sky, and generally included comets and the Sun and Moon. With the Copernican revolution, the Earth was recognized as a planet, and the Sun was seen to be fundamentally different. The Galilean satellites of Jupiter were at first called planets (satellite planets), but later reclassified along with the Moon. The first asteroids were also considered to be planets, but were reclassified when it was realized that there were a great many of them, crossing each other's orbits, in a zone where only a single planet had been expected. Likewise, Pluto was found where an outer planet had been expected, but doubts were raised when it turned out to cross Neptune's orbit and to be much smaller than the expectation required. When Eris, an outer body more massive than Pluto, was discovered, the International Astronomical Union (IAU) officially defined the word planet as above. However, a significant number of astronomers reject the IAU definition, especially in the field of planetary geology. Some are of the opinion that orbital parameters should be irrelevant, and that either any equilibrium (ellipsoidal) body in direct orbit around a star is a planet (there are likely at least a dozen such bodies in the Solar system) or that any equilibrium body at all is a planet, thus re-accepting the Moon, the Galilean satellites and other large moons as planets, as well as rogue planets.

上位語

• planemo

下位語

派生語

関連する語

参考

• planets of the Solar System: Mercury · Venus · Earth · Mars · Jupiter · Saturn · Uranus · Neptune
• moon
• orbit

参照

• planet on Wikipedia.Wikipedia
• Planets in astrology on Wikipedia.Wikipedia
• First Steps to Astronomy and Geography, 1828, (Hatchard & Son: Piccadilly, London).

アナグラム

• Plante, pental, platen