Haumea

136108 Haumea
	Low-resolution Hubble Space Telescope image of Haumea and its two moons, Hi'iaka (top) and Namaka (bottom), June 2015
Discovery
Discovered by	Brown et al.; Ortiz et al.;
Discovery date	March 7, 2003 (Ortiz); December 28, 2004 (Brown);
Designations
MPC designation	(136108) Haumea
Pronunciation	/haʊˈmeɪ.ə, ˌhɑːuː-/
Named after	Haumea
Alternative designations	2003 EL61
Minor planet category	Dwarf planet; TNO; Haumea family; trinary;
Adjectives	Haumean
Symbol	(mostly astrological)
Orbital characteristics
	Epoch December 17, 2020 (JD 2459200.5)
	Uncertainty parameter 2
Observation arc	65 years and 291 days (24033 days)
Earliest precovery date	March 22, 1955
Aphelion	51.585 AU (7.7170 Tm)
Perihelion	34.647 AU (5.1831 Tm)
Semi-major axis	43.116 AU (6.4501 Tm)
Eccentricity	0.19642
Orbital period (sidereal)	283.12 yr (103,410 days)
Average orbital speed	4.53 km/s
Mean anomaly	218.205°
Mean motion	0° 0m 12.533s / day
Inclination	28.2137°
Longitude of ascending node	122.167°
Time of perihelion	≈ June 1, 2133; ±2 days
Argument of perihelion	239.041°
Known satellites	2 (Hiʻiaka and Namaka)
Physical characteristics
Dimensions	≈ 2,100 × 1,680 × 1,074 km; 2,322±60 × 1,704±8 × 1,026±32 km;
Mean radius	≈ 780 km; 798±6 km to 816 km;
Surface area	≈ 8.14×106 km2
Volume	≈ 1.98×109 km3; 0.0018 Earths
Mass	(4.006±0.040)×1021 kg; 0.00066 Earths
Mean density	≈ 2.018 g/cm3; 1.885±0.080 g/cm3 to 1.757 g/cm3;
Equatorial surface gravity	0.93 m/s2 at poles; to 0.24 m/s2 at longest axis
Equatorial escape velocity	1 km/s at poles; to 0.71 km/s at longest axis
Sidereal rotation period	3.915341±0.000005 h; (0.163139208 d)
Axial tilt	≈ 126° (to orbit; assumed); 81.2° or 78.9° (to ecliptic)
North pole right ascension	282.6°±1.2°
North pole declination	−13.0°±1.3° or −11.8°±1.2°
Geometric albedo	≈ 0.66 geometric; ≤ 0.51±0.02 geometric; 0.33±0.03 Bond;
Temperature	< 50 K
Spectral type	BB (neutral); B−V = 0.64, V−R = 0.33 ; B0−V0 = 0.646 ;
Apparent magnitude	17.3 (opposition)
Absolute magnitude (H)	0.428±0.011 (V-band) · 0.2

Haumea (minor-planet designation 136108 Haumea) is a dwarf planet located beyond Neptune's orbit.^[25] It was discovered in 2004 by a team headed by Mike Brown of Caltech at the Palomar Observatory, and formally announced in 2005 by a team headed by José Luis Ortiz Moreno at the Sierra Nevada Observatory in Spain, who had discovered it that year in precovery images taken by the team in 2003. From that announcement, it received the provisional designation 2003 EL61. On September 17, 2008, it was named after Haumea, the Hawaiian goddess of childbirth, under the expectation by the International Astronomical Union (IAU) that it would prove to be a dwarf planet. Nominal estimates make it the third-largest known trans-Neptunian object, after Eris and Pluto, and approximately the size of Uranus's moon Titania. Precovery images of Haumea have been identified back to March 22, 1955.^[9]

Haumea's mass is about one-third that of Pluto, and 1/1400 that of Earth. Although its shape has not been directly observed, calculations from its light curve are consistent with it being a Jacobi ellipsoid (the shape it would be if it were a dwarf planet), with its major axis twice as long as its minor. In October 2017, astronomers announced the discovery of a ring system around Haumea, representing the first ring system discovered for a trans-Neptunian object and a dwarf planet. Haumea's gravity was until recently thought to be sufficient for it to have relaxed into hydrostatic equilibrium, though that is now unclear. Haumea's elongated shape together with its rapid rotation, rings, and high albedo (from a surface of crystalline water ice), are thought to be the consequences of a giant collision, which left Haumea the largest member of a collisional family that includes several large trans-Neptunian objects and Haumea's two known moons, Hiʻiaka and Namaka.

^ New dwarf planet named for Hawaiian goddess Archived 2015-12-08 at the Wayback Machine (HeraldNet, September 19, 2008)
^ "DPS08 Webstreaming". Archived from the original on 2009-01-06. Retrieved 2009-02-14.
^ "365 Days of Astronomy". Archived from the original on 2012-02-20. Retrieved 2009-04-11.
^ Cite error: The named reference K10H75 was invoked but never defined (see the help page).
^ Cite error: The named reference Buie was invoked but never defined (see the help page).
^ Cite error: The named reference candidate was invoked but never defined (see the help page).
^ E.g. Giovanni Vulpetti (2013) Fast Solar Sailing, p. 333.
^ Cite error: The named reference MPC-object was invoked but never defined (see the help page).
^ ^a ^b ^c Cite error: The named reference jpldata was invoked but never defined (see the help page).
^ Cite error: The named reference perihelion was invoked but never defined (see the help page).
^ ^a ^b Cite error: The named reference Dunham2019 was invoked but never defined (see the help page).
^ ^a ^b ^c ^d Cite error: The named reference Ortiz2017 was invoked but never defined (see the help page).
^ "Ellipsoid surface area: 8.13712×10^6 km²". wolframalpha.com. 20 December 2019. Archived from the original on 25 July 2020. Retrieved 20 December 2019.
^ "Ellipsoid volume: 1.98395×10^9 km³". wolframalpha.com. 20 December 2019. Archived from the original on 25 July 2020. Retrieved 20 December 2019.
^ Cite error: The named reference RagozzineBrown2009 was invoked but never defined (see the help page).
^ ^a ^b Cite error: The named reference TNOsCool12 was invoked but never defined (see the help page).
^ ^a ^b ^c Cite error: The named reference Kondratyev2018 was invoked but never defined (see the help page).
^ Cite error: The named reference coordstransform was invoked but never defined (see the help page).
^ Cite error: The named reference Verbiscer2022 was invoked but never defined (see the help page).
^ Cite error: The named reference Trujillo 2006 was invoked but never defined (see the help page).
^ Cite error: The named reference Snodgrass2009 was invoked but never defined (see the help page).
^ Cite error: The named reference Rabinowitz2008 was invoked but never defined (see the help page).
^ Cite error: The named reference AstDys was invoked but never defined (see the help page).
^ Cite error: The named reference Horizons was invoked but never defined (see the help page).
^ Cite error: The named reference iau was invoked but never defined (see the help page).

Cite error: There are <ref group=nb> tags on this page, but the references will not show without a {{reflist|group=nb}} template (see the help page).

[1] New dwarf planet named for Hawaiian goddess Archived 2015-12-08 at the Wayback Machine (HeraldNet, September 19, 2008)

[2] "DPS08 Webstreaming". Archived from the original on 2009-01-06. Retrieved 2009-02-14.

[3] "365 Days of Astronomy". Archived from the original on 2012-02-20. Retrieved 2009-04-11.

[K10H75-5] Cite error: The named reference K10H75 was invoked but never defined (see the help page).

[Buie-6] Cite error: The named reference Buie was invoked but never defined (see the help page).

[candidate-7] Cite error: The named reference candidate was invoked but never defined (see the help page).

[8] E.g. Giovanni Vulpetti (2013) Fast Solar Sailing, p. 333.

[MPC-object-9] Cite error: The named reference MPC-object was invoked but never defined (see the help page).

[jpldata-10] Cite error: The named reference jpldata was invoked but never defined (see the help page).

[perihelion-12] Cite error: The named reference perihelion was invoked but never defined (see the help page).

[Dunham2019-13] Cite error: The named reference Dunham2019 was invoked but never defined (see the help page).

[Ortiz2017-15] Cite error: The named reference Ortiz2017 was invoked but never defined (see the help page).

[Wolfram1-18] "Ellipsoid surface area: 8.13712×10^6 km²". wolframalpha.com. 20 December 2019. Archived from the original on 25 July 2020. Retrieved 20 December 2019.

[Wolfram2-19] "Ellipsoid volume: 1.98395×10^9 km³". wolframalpha.com. 20 December 2019. Archived from the original on 25 July 2020. Retrieved 20 December 2019.

[RagozzineBrown2009-20] Cite error: The named reference RagozzineBrown2009 was invoked but never defined (see the help page).

[TNOsCool12-21] Cite error: The named reference TNOsCool12 was invoked but never defined (see the help page).

[Kondratyev2018-22] Cite error: The named reference Kondratyev2018 was invoked but never defined (see the help page).

[coordstransform-23] Cite error: The named reference coordstransform was invoked but never defined (see the help page).

[Verbiscer2022-25] Cite error: The named reference Verbiscer2022 was invoked but never defined (see the help page).

[Trujillo_2006-26] Cite error: The named reference Trujillo 2006 was invoked but never defined (see the help page).

[Snodgrass2009-27] Cite error: The named reference Snodgrass2009 was invoked but never defined (see the help page).

[Rabinowitz2008-28] Cite error: The named reference Rabinowitz2008 was invoked but never defined (see the help page).

[AstDys-29] Cite error: The named reference AstDys was invoked but never defined (see the help page).

[Horizons-30] Cite error: The named reference Horizons was invoked but never defined (see the help page).

[iau-31] Cite error: The named reference iau was invoked but never defined (see the help page).

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Discovery
Low-resolution Hubble Space Telescope image of Haumea and its two moons, Hi'iaka (top) and Namaka (bottom), June 2015
Discovered by	Brown et al. Ortiz et al.
Discovery date	March 7, 2003 (Ortiz) December 28, 2004 (Brown)
Designations
MPC designation	(136108) Haumea
Pronunciation	/haʊˈmeɪ.ə, ˌhɑːuː-/^{[nb 1]}
Named after	Haumea
Alternative designations	2003 EL₆₁
Minor planet category	Dwarf planet TNO^[4]^[5] Haumea family trinary^[6]
Adjectives	Haumean^[7]
Symbol	(mostly astrological)
Orbital characteristics^[8]
Epoch December 17, 2020 (JD 2459200.5)
Uncertainty parameter 2
Observation arc	65 years and 291 days (24033 days)
Earliest precovery date	March 22, 1955
Aphelion	51.585 AU (7.7170 Tm)
Perihelion	34.647 AU (5.1831 Tm)
Semi-major axis	43.116 AU (6.4501 Tm)
Eccentricity	0.19642
Orbital period (sidereal)	283.12 yr (103,410 days)^[9]
Average orbital speed	4.53 km/s^{[nb 2]}
Mean anomaly	218.205°
Mean motion	0° 0^m 12.533^s / day
Inclination	28.2137°
Longitude of ascending node	122.167°
Time of perihelion	≈ June 1, 2133^[10] ±2 days
Argument of perihelion	239.041°
Known satellites	2 (Hiʻiaka and Namaka)
Physical characteristics
Dimensions	≈ 2,100 × 1,680 × 1,074 km^{[nb 3]}^[11] 2,322±60 × 1,704±8 × 1,026±32 km^{[nb 4]}^[12]
Mean radius	≈ 780 km^{[nb 3]} 798±6 km to 816 km^{[nb 5]}
Surface area	≈ 8.14×10⁶ km²^{[nb 3]}^[13]
Volume	≈ 1.98×10⁹ km³^{[nb 3]}^[14] 0.0018 Earths
Mass	(4.006±0.040)×10²¹ kg^[15] 0.00066 Earths
Mean density	≈ 2.018 g/cm³^{[nb 3]} 1.885±0.080 g/cm³ to 1.757 g/cm³^{[nb 5]}
Equatorial surface gravity	0.93 m/s² at poles to 0.24 m/s² at longest axis
Equatorial escape velocity	1 km/s at poles to 0.71 km/s at longest axis
Sidereal rotation period	3.915341±0.000005 h^[16] (0.163139208 d)
Axial tilt	≈ 126° (to orbit; assumed) 81.2° or 78.9° (to ecliptic)^{[nb 6]}
North pole right ascension	282.6°±1.2°^[17]^: 3174
North pole declination	−13.0°±1.3° or −11.8°±1.2°^[17]^: 3174
Geometric albedo	≈ 0.66 geometric^{[nb 3]} ≤ 0.51±0.02 geometric^[12] 0.33±0.03 Bond^[19]
Temperature	< 50 K^[20]
Spectral type	BB (neutral) B−V = 0.64, V−R = 0.33 ^[21] B₀−V₀ = 0.646 ^[22]
Apparent magnitude	17.3 (opposition)^[23]^[24]
Absolute magnitude (H)	0.428±0.011 (V-band) ^[16] · 0.2 ^[9]

Haumea

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