Back Pluto Afrikaans Pluto ALS ፕሉቶ Amharic Plutón (astronomía) AN Pluto ANG यम (बौना ग्रह) ANP بلوتو Arabic پلوطو ARY بلوتو (كوكب) ARZ প্লুটো Assamese
 | |||||||||
| Discovery | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Discovered by | Clyde W. Tombaugh | ||||||||
| Discovery date | February 18, 1930 | ||||||||
| Designations | |||||||||
| MPC designation | 134340 Pluto | ||||||||
| Pronunciation | /ˈpluːtoʊ/ ( listen),[note 1] | ||||||||
| dwarf planet, TNO, plutoid, KBO, plutino | |||||||||
| Adjectives | Plutonian | ||||||||
| Orbital characteristics | |||||||||
| Epoch J2000 | |||||||||
| Aphelion | 7,375,927,931 km 49.305 032 87 AU | ||||||||
| Perihelion | 4,436,824,613 km 29.658 340 67 AU | ||||||||
| 5,906,376,272 km 39.481 686 77 AU | |||||||||
| Eccentricity | 0.248 807 66 | ||||||||
| 90,613.305 days 248.09 years 14,164.4 Pluto solar days[1] | |||||||||
| 366.73 days | |||||||||
Average orbital speed | 4.666 km/s | ||||||||
| Inclination | 17.141 75° 11.88° to Sun's equator | ||||||||
| 110.303 47° | |||||||||
| 113.763 29° | |||||||||
| Known satellites | 5 | ||||||||
| Physical characteristics | |||||||||
Mean radius | 1,187 ± 4 km[2] 0.18 Earths | ||||||||
| 1.665×107 km²[note 2] 0.033 Earths | |||||||||
| Volume | 6,39×109 km³[note 3] 0.0059 Earths | ||||||||
| Mass | (1.305 ± 0.007)×1022 kg[3] 0.002 1 Earths 0.178 moon | ||||||||
Mean density | 2.03 ± 0.06 g/cm³[3] | ||||||||
| 0.658 m/s²[note 4] 0.067 g | |||||||||
| 1.229 km/s[note 5] | |||||||||
Sidereal rotation period | −6.387 230 day 6 d 9 h 17 m 36 s | ||||||||
Equatorial rotation velocity | 47.18 km/h | ||||||||
| 119.591 ± 0.014° (to orbit)[3][note 6] | |||||||||
North pole right ascension | 133.046 ± 0.014°[3] | ||||||||
North pole declination | −6.145 ± 0.014°[3] | ||||||||
| Albedo | 0.49–0.66 (varies by 35%)[4][5] | ||||||||
| |||||||||
| up to 13.65 (mean is 15.1)[5] | |||||||||
| −0.7[6] | |||||||||
| Atmosphere | |||||||||
Surface pressure | 0.30 Pa (summer maximum) | ||||||||
| Composition by volume | nitrogen, methane, carbon monoxide | ||||||||
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Pluto is a dwarf planet in the Solar System.[7] Its formal name is 134340 Pluto, and its planetary symbol .svg){kind=small}
[8] or .svg){kind=small}
.[9] Pluto is the ninth largest body that moves around the Sun. Upon first being discovered, Pluto was considered a planet but was reclassified to a dwarf planet in 2006. It is the largest body in the Kuiper belt.
Like other members of the Kuiper belt, Pluto is mainly made of rock and ice. It is quite small. It is about a fifth (⅕) of the weight of the Earth's Moon. It is only a third (⅓) of its volume. Pluto is very far from the Sun, so its temperature is very low. The average temperature on Pluto is -226 to -240 degrees Celsius.[10] It has an odd orbit and this orbit is very sloped. It takes Pluto to 30 to 49 AU (4.4–7.4 billion km) from the Sun. This causes Pluto to sometimes go closer to the Sun than Neptune.
Since it was discovered in 1930, Pluto was thought to be the Solar System's ninth planet. In the late 1970s, the minor planet 2060 Charon was found and people learned that Pluto had a small size.[11]
Later, in the early 21st century, the scattered disc object Eris and other objects like Pluto were discovered. Eris was initially believed to be 27% larger than Pluto, but was later found to be slightly smaller.[12] On August 24, 2006, the International Astronomical Union (IAU) gave a definition to the word "planet" for the first time. By this definition, Pluto was not a planet anymore. It became a "dwarf planet" along with Eris and Ceres.[13] After this, Pluto was put on the list of minor planets and was downgraded in 2006 by astronomer Michael E Brown.[14] It was given the number 134340.[15][16] Some scientists still think that Pluto should be classified as a planet.[17]
Cite error: There are <ref group=note> tags on this page, but the references will not show without a {{reflist|group=note}} template (see the help page).
- ↑ Seligman, Courtney. "Rotation Period and Day Length". Retrieved 2009-08-13.
- ↑ Stern, S. A.; et al. (16 October 2015), "The Pluto system: Initial results from its exploration by New Horizons", Science, 350 (6258): aad1815-1–aad1815-8, arXiv:1510.07704, Bibcode:2015Sci...350.1815S, doi:10.1126/science.aad1815, ISSN 0036-8075, PMID 26472913, S2CID 1220226
- ↑ 3.0 3.1 3.2 3.3 3.4 M.W. Buie, W.M. Grundy, E.F. Young, L.A. Young, S.A. Stern (2006). "Orbits and photometry of Pluto's satellites: Charon, S/2005 P1, and S/2005 P2". Astronomical Journal. 132 (1): 290–298. arXiv:astro-ph/0512491. Bibcode:2006AJ....132..290B. doi:10.1086/504422. S2CID 119386667.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ↑ Calvin J. Hamilton (2006-02-12). "Dwarf Planet Pluto". Views of the Solar System. Retrieved 2007-01-10.
- ↑ 5.0 5.1 David R. Williams. "Planetary Fact Sheet". NASA. Retrieved 2007-03-31.
- ↑ "JPL Small-Body Database Browser: 134340 Pluto". Retrieved 2008-06-12.
- ↑ "Pluto Overview". Retrieved September 9, 2018.
- ↑ JPL/NASA (2015-04-22). "What is a Dwarf Planet?". Jet Propulsion Laboratory. Retrieved 2022-01-19.
- ↑ John Lewis, ed. (2004). Physics and chemistry of the solar system (2 ed.). Elsevier. p. 64. ISBN 9780124467446.
- ↑ "In Depth | Pluto". NASA Solar System Exploration. Retrieved 2021-10-08.
- ↑ Ian Ridpath (December 1978). "Pluto—Planet or Impostor?" (PDF). Astronomy: 6–11. Archived from the original (PDF) on 2012-08-07. Retrieved 2010-05-02.
- ↑ "Astronomers Measure Mass of Largest Dwarf Planet". hubblesite. 2007. Retrieved 2007-11-03.
- ↑ A. Akwagyiram (2005). "Farewell Pluto?". BBC News. Retrieved 2006-03-05.
- ↑ Ghosh, Pallab (2015-07-14). "Man who 'killed Pluto' has no regrets". Retrieved 2019-02-18.
- ↑ T.B. Spahr (2006). "MPEC 2006-R19 : Editorial Notice". Minor Planet Center. Retrieved 2006-09-07.
- ↑ D. Shiga (2006). "Pluto added to official "minor planet" list". NewScientist. Retrieved 2006-09-08.
- ↑ Richard Gray (2008-08-10). "Pluto should get back planet status, say astronomers". The Telegraph. Archived from the original on 2008-08-12. Retrieved 2008-08-09.