Charon (moon)

Charon
	Charon as imaged by the New Horizons spacecraft, July 2015. A massive fault system involving Serenity Chasma and Mandjet Chasma crosses Charon's equator, while Charon's north pole is covered by the dark Mordor Macula
Discovery
Discovered by	James W. Christy
Discovery date	June 22, 1978
Designations
Designation	Pluto I
Pronunciation	/ˈkɛərɒn, -ən/ KAIR-on, -⁠ən or /ˈʃærən/ SHAIR-ən
Named after	Discoverer's wife, Charlene, and Χάρων Kharōn
Alternative names	S/1978 P 1
Adjectives	Charonian; Charontian, -ean; Charonean
Orbital characteristics
	Epoch 2452600.5; (2002 Nov 22)
Periapsis	19 592.61 km
Apoapsis	19 598.92 km
Semi-major axis	19595.764+0.007; −0.008 km (planetocentric); 17181.0 km (barycentric)
Eccentricity	0.000161
Orbital period (sidereal)	6.387221+0.000005; −0.000003 d; (6 d, 9 h, 17 m, 35.89 ± 0.35 s)
Average orbital speed	0.21 km/s
Inclination	0.080° (to Pluto's equator); 119.591°±0.014° (to Pluto's orbit); 112.783°±0.014° (to the ecliptic)
Longitude of ascending node	223.046°±0.014° (to vernal equinox)
Satellite of	Pluto
Physical characteristics
Mean radius	606.0±0.5 km (0.095 Earths, 0.51 Plutos)
Flattening	<0.5%
Surface area	4.6×106 km2 (0.0090 Earths)
Volume	(9.32±0.14)×108 km3 (0.00086 Earths)
Mass	(1.5897±0.0045)×1021 kg; (2.66×10−4 Earths); (12.2% of Pluto)
Mean density	1.705±0.006 g/cm3
Surface gravity	0.288 m/s2
Escape velocity	0.59 km/s; 0.37 mi/s
Synodic rotation period	synchronous
Albedo	0.2 to 0.5 at a solar phase angle of 15°
Temperature	−220 °C (53 K)
Apparent magnitude	16.8
Absolute magnitude (H)	1
Angular diameter	55 milli-arcsec

Charon (/ˈkɛərɒn, -ən/ KAIR-on, -⁠ən or /ˈʃærən/ SHAIR-ən),^{[note 1]} known as (134340) Pluto I, is the largest of the five known natural satellites of the dwarf planet Pluto. It has a mean radius of 606 km (377 mi). Charon is the sixth-largest known trans-Neptunian object after Pluto, Eris, Haumea, Makemake, and Gonggong.^[18] It was discovered in 1978 at the United States Naval Observatory in Washington, D.C., using photographic plates taken at the United States Naval Observatory Flagstaff Station (NOFS).

With half the diameter and one-eighth the mass of Pluto, Charon is a very large moon in comparison to its parent body. Its gravitational influence is such that the barycenter of the Plutonian system lies outside Pluto, and the two bodies are tidally locked to each other.^[19] The dwarf planet systems Pluto–Charon and Eris–Dysnomia are the only known examples of mutual tidal locking in the Solar System,^[20] though it is likely that Orcus–Vanth is another.^[21]

The reddish-brown cap of the north pole of Charon is composed of tholins, organic macromolecules that may be essential ingredients of life. These tholins were produced from methane, nitrogen, and related gases which may have been released by cryovolcanic eruptions on the moon,^[22]^[23] or may have been transferred over 19,000 km (12,000 mi) from the atmosphere of Pluto to the orbiting moon.^[24]

The New Horizons spacecraft is the only probe that has visited the Pluto system. It approached Charon to within 27,000 km (17,000 mi) in 2015.

^ Jennifer Blue (November 9, 2009). "Gazetteer of Planetary Nomenclature". IAU Working Group for Planetary System Nomenclature (WGPSN). Retrieved February 24, 2010.
^ Cite error: The named reference OED was invoked but never defined (see the help page).
^ Cite error: The named reference Sharon was invoked but never defined (see the help page).
^ C.T. Russell (2009) New Horizons: Reconnaissance of the Pluto–Charon System and the Kuiper Belt, p. 96
^ Kathryn Bosher (2012) Theater outside Athens: Drama in Greek Sicily and South Italy, pp 100, 104–105
^ Bowman et al. (1979) Studies in Honor of Gerald E. Wade, p. 125–126
^ William Herbert (1838) Attila, King of the Huns, p.48
^ Tatiana Kontou (2009) Spiritualism and Women's Writing: From the Fin de Siècle to the Neo-Victorian, p. 60 ff
^ Cite error: The named reference Buie_2006 was invoked but never defined (see the help page).
^ ^a ^b ^c ^d ^e Cite error: The named reference Brozovic2024 was invoked but never defined (see the help page).
^ Cite error: The named reference JPL_Pluto was invoked but never defined (see the help page).
^ Cite error: The named reference Stern_2015 was invoked but never defined (see the help page).
^ Cite error: The named reference Stern_2017 was invoked but never defined (see the help page).
^ Cite error: The named reference Nimmo2017 was invoked but never defined (see the help page).
^ "Classic Satellites of the Solar System". Observatorio ARVAL. April 15, 2007. Archived from the original on July 31, 2010. Retrieved October 19, 2007.
^ David Jewitt (June 2008). "The 1000 km Scale KBOs". Institute for Astronomy (UH). Retrieved June 13, 2008.
^ "Measuring the Size of a Small, Frost World" (Press release). European Southern Observatory. January 4, 2006. Archived from the original on January 18, 2006. Retrieved October 19, 2007.
^ "Trans-Neptunian objects".
^ Michael Borgia (2006). My History: Human Vision and The Night Sky: How to Improve Your Observing Skills. Springer Science & Business Media. p. 201. ISBN 9780387463223.
^ Szakáts, R.; Kiss, Cs.; Ortiz, J. L.; Morales, N.; Pál, A.; Müller, T. G.; et al. (2023). "Tidally locked rotation of the dwarf planet (136199) Eris discovered from long-term ground based and space photometry". Astronomy & Astrophysics. L3: 669. arXiv:2211.07987. Bibcode:2023A&A...669L...3S. doi:10.1051/0004-6361/202245234. S2CID 253522934.
^ Brown, Michael E.; Butler, Bryan (July 2023). "Masses and densities of dwarf planet satellites measured with ALMA". The Planetary Science Journal. 4 (10): 11. arXiv:2307.04848. Bibcode:2023PSJ.....4..193B. doi:10.3847/PSJ/ace52a.
^ Yirka, Bob (September 7, 2022). "A new explanation for the reddish north pole of Pluto's moon Charon". Phys.org. Retrieved September 9, 2022.
^ Menten, s.M.; et al. (August 9, 2022). "Endogenically sourced volatiles on Charon and other Kuiper belt objects". Nature Communications. 13 (1): 4457. Bibcode:2022NatCo..13.4457M. doi:10.1038/s41467-022-31846-8. PMC 9363412. PMID 35945207.
^ Bromwich, Jonah Engel; St. Fleur, Nicholas (September 14, 2016). "Why Pluto's Moon Charon Wears a Red Cap". The New York Times. Retrieved September 14, 2016.

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).

[Nomenclature-1] Jennifer Blue (November 9, 2009). "Gazetteer of Planetary Nomenclature". IAU Working Group for Planetary System Nomenclature (WGPSN). Retrieved February 24, 2010.

[OED-2] Cite error: The named reference OED was invoked but never defined (see the help page).

[Sharon-3] Cite error: The named reference Sharon was invoked but never defined (see the help page).

[6] C.T. Russell (2009) New Horizons: Reconnaissance of the Pluto–Charon System and the Kuiper Belt, p. 96

[7] Kathryn Bosher (2012) Theater outside Athens: Drama in Greek Sicily and South Italy, pp 100, 104–105

[9] Bowman et al. (1979) Studies in Honor of Gerald E. Wade, p. 125–126

[10] William Herbert (1838) Attila, King of the Huns, p.48

[12] Tatiana Kontou (2009) Spiritualism and Women's Writing: From the Fin de Siècle to the Neo-Victorian, p. 60 ff

[Buie_2006-13] Cite error: The named reference Buie_2006 was invoked but never defined (see the help page).

[Brozovic2024-14] Cite error: The named reference Brozovic2024 was invoked but never defined (see the help page).

[JPL_Pluto-16] Cite error: The named reference JPL_Pluto was invoked but never defined (see the help page).

[Stern_2015-17] Cite error: The named reference Stern_2015 was invoked but never defined (see the help page).

[Stern_2017-18] Cite error: The named reference Stern_2017 was invoked but never defined (see the help page).

[Nimmo2017-19] Cite error: The named reference Nimmo2017 was invoked but never defined (see the help page).

[magnitude-20] "Classic Satellites of the Solar System". Observatorio ARVAL. April 15, 2007. Archived from the original on July 31, 2010. Retrieved October 19, 2007.

[jewitt1000km-21] David Jewitt (June 2008). "The 1000 km Scale KBOs". Institute for Astronomy (UH). Retrieved June 13, 2008.

[22] "Measuring the Size of a Small, Frost World" (Press release). European Southern Observatory. January 4, 2006. Archived from the original on January 18, 2006. Retrieved October 19, 2007.

[23] "Trans-Neptunian objects".

[24] Michael Borgia (2006). My History: Human Vision and The Night Sky: How to Improve Your Observing Skills. Springer Science & Business Media. p. 201. ISBN 9780387463223.

[Szakats2022-25] Szakáts, R.; Kiss, Cs.; Ortiz, J. L.; Morales, N.; Pál, A.; Müller, T. G.; et al. (2023). "Tidally locked rotation of the dwarf planet (136199) Eris discovered from long-term ground based and space photometry". Astronomy & Astrophysics. L3: 669. arXiv:2211.07987. Bibcode:2023A&A...669L...3S. doi:10.1051/0004-6361/202245234. S2CID 253522934.

[Brown2023-26] Brown, Michael E.; Butler, Bryan (July 2023). "Masses and densities of dwarf planet satellites measured with ALMA". The Planetary Science Journal. 4 (10): 11. arXiv:2307.04848. Bibcode:2023PSJ.....4..193B. doi:10.3847/PSJ/ace52a.

[PHY-20220907-27] Yirka, Bob (September 7, 2022). "A new explanation for the reddish north pole of Pluto's moon Charon". Phys.org. Retrieved September 9, 2022.

[NC-20220809-28] Menten, s.M.; et al. (August 9, 2022). "Endogenically sourced volatiles on Charon and other Kuiper belt objects". Nature Communications. 13 (1): 4457. Bibcode:2022NatCo..13.4457M. doi:10.1038/s41467-022-31846-8. PMC 9363412. PMID 35945207.

[NYT-20160914-29] Bromwich, Jonah Engel; St. Fleur, Nicholas (September 14, 2016). "Why Pluto's Moon Charon Wears a Red Cap". The New York Times. Retrieved September 14, 2016.

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Discovery
Charon as imaged by the New Horizons spacecraft, July 2015. A massive fault system involving Serenity Chasma and Mandjet Chasma crosses Charon's equator, while Charon's north pole is covered by the dark Mordor Macula
Discovered by	James W. Christy
Discovery date	June 22, 1978
Designations
Designation	Pluto I^[1]
Pronunciation	/ˈkɛərɒn, -ən/ KAIR-on, -⁠ən^[2] or /ˈʃærən/ SHAIR-ən^[3]^{[note 1]}
Named after	Discoverer's wife, Charlene, and Χάρων Kharōn
Alternative names	S/1978 P 1
Adjectives	Charonian^{[note 2]}^[4]^[5] Charontian, -ean^{[note 3]}^[6]^[7] Charonean^{[note 4]}^[8]
Orbital characteristics ^[9]
Epoch 2452600.5 (2002 Nov 22)
Periapsis	19 592.61 km
Apoapsis	19 598.92 km
Semi-major axis	19595.764+0.007 −0.008 km (planetocentric)^[10] 17181.0 km (barycentric)
Eccentricity	0.000161^[10]
Orbital period (sidereal)	6.387221+0.000005 −0.000003 d (6 d, 9 h, 17 m, 35.89 ± 0.35 s)^[10]
Average orbital speed	0.21 km/s^{[note 5]}
Inclination	0.080° (to Pluto's equator)^[11] 119.591°±0.014° (to Pluto's orbit) 112.783°±0.014° (to the ecliptic)
Longitude of ascending node	223.046°±0.014° (to vernal equinox)
Satellite of	Pluto
Physical characteristics
Mean radius	606.0±0.5 km^[12]^[13] (0.095 Earths, 0.51 Plutos)
Flattening	<0.5%^[14]
Surface area	4.6×10⁶ km² (0.0090 Earths)
Volume	(9.32±0.14)×10⁸ km³ (0.00086 Earths)
Mass	(1.5897±0.0045)×10²¹ kg^[10] (2.66×10⁻⁴ Earths) (12.2% of Pluto)
Mean density	1.705±0.006 g/cm³^[10]
Surface gravity	0.288 m/s²
Escape velocity	0.59 km/s 0.37 mi/s
Synodic rotation period	synchronous
Albedo	0.2 to 0.5 at a solar phase angle of 15°
Temperature	−220 °C (53 K)
Apparent magnitude	16.8^[15]
Absolute magnitude (H)	1^[16]
Angular diameter	55 milli-arcsec^[17]

Charon (moon)

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