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Moons of Haumea

Namaka
2003 EL61 Haumea, with moons.jpg
Namaka is the faint spot near the bottom of the photo, directly below Haumea (center), in this Keck telescope image.
Discovery
Discovered by Michael E. Brown,
Chad Trujillo,
David Rabinowitz, et al.
Discovery date 30 June 2005
Designations
MPC designation Haumea II Namaka
Pronunciation /nɑːˈmɑːkə/ nah-MAH-kə
(136108) 2003 EL61 II,
S/2005 (2003 EL61) 2
Orbital characteristics
Epoch JD 2454615.0
25657±91 km
Eccentricity 0.249±0.015 (in 2009; variable)
18.2783±0.0076 d
178.5°±1.7°
Inclination 113.013°±0.075°
13.41°±0.08° relative to Hiʻiaka (in 2008; variable)
205.016°±0.228°
178.9°±2.3°
Satellite of Haumea
Physical characteristics
Mean radius
~85 km (if albedo is same as primary's 0.7±0.1)
Mass 1.79 ± 1.48×1018kg
(0.05% the mass of Haumea)
Mean density
(assumed to be near 1 g/cm3)
Albedo 0.8±0.2
Temperature 32±3 K
21.9 (4.6 difference from primary's 17.3)
Hiʻiaka
2003 EL61 Haumea, with moons.jpg
Hiʻiaka is above Haumea (center) in this Keck telescope image.
Discovery
Discovered by Michael E. Brown,
Chad Trujillo,
David Rabinowitz, et al.
Discovery date 26 January 2005
Designations
MPC designation Haumea I Hiʻiaka
Pronunciation /ˌhʔiˈɑːkə/
(136108) 2003 EL61 I,
S/2005 (2003 EL61) 1
Orbital characteristics
49880±198 km
Eccentricity 0.0513±0.0078
49.12±0.03 d
Inclination 126.356±0.064°
Satellite of Haumea
Physical characteristics
Mean radius
~160 km
Mass (1.79±0.11)×1019 kg (0.45% of Haumea)
Mean density
~1 g/cm3
Temperature 32±K
20.3 (3.0 difference from primary's 17.3)

The outer Solar System dwarf planet Haumea has two known moons, Hiʻiaka and Namaka, named after Hawaiian goddesses. These small moons were discovered in 2005, from observations of Haumea made at the large telescopes of the W. M. Keck Observatory in Hawaii.

Haumea's moons are unusual in a number of ways. They are thought to be part of its extended collisional family, which formed billions of years ago from icy debris after a large impact disrupted Haumea's ice mantle. Hiʻiaka, the larger, outermost moon, has large amounts of pure water ice on its surface, which is rare among Kuiper belt objects. Namaka, about one tenth the mass, has an orbit with surprising dynamics: it is unusually eccentric and appears to be greatly influenced by the larger satellite.

Two small satellites were discovered around Haumea (which was at that time still designated 2003 EL61) through observations using the W.M. Keck Observatory by a Caltech team in 2005. The outer and larger of the two satellites was discovered January 26, 2005, and formally designated S/2005 (2003 EL61) 1, though nicknamed "Rudolph" by the Caltech team. The smaller, inner satellite of Haumea was discovered on June 30, 2005, formally termed S/2005 (2003 EL61) 2, and nicknamed "Blitzen". On September 7, 2006, both satellites were numbered and admitted into the official minor planet catalogue as (136108) 2003 EL61 I and II, respectively.


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