Namaka (moon)

Namaka is the smaller, inner moon of the trans-Neptunian dwarf planet Haumea. Discovered in 2005, it is named after Nāmaka, the goddess of the sea in Hawaiian mythology and one of the daughters of Haumea. Namaka is notable for its unusual, highly-perturbed orbit that is heavily influenced by the larger, outer moon Hi'iaka.

Namaka

In this photo taken by the Hubble Space Telescope, Namaka is the faint spot near the bottom, directly below Haumea (center).
Discovery
Discovered by	Michael E. Brown, Chad Trujillo, David Rabinowitz, et al.
Discovery date	30 June 2005
Designations
Designation	Haumea II (136108) Haumea II Namaka
Pronunciation	/nɑːˈmɑːkə/ Hawaiian: [naːˈmɐkə]
Alternative names	(136108) 2003 EL61 II S/2005 (2003 EL61) 2
Orbital characteristics[1]
Epoch JD 2454615.0
Semi-major axis	25657±91 km[1]
Eccentricity	0.249±0.015 (in 2009; variable)
Orbital period (sidereal)	18.2783±0.0076 d[1]
Mean anomaly	178.5°±1.7°
Inclination	113.013°±0.075° 13.41°±0.08° relative to Hiʻiaka (in 2008; variable)
Longitude of ascending node	205.016°±0.228°
Argument of perihelion	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)×1018 kg[1] (0.05% the mass of Haumea)
Mean density	(assumed to be near 1 g/cm3)
Synodic rotation period	?
Albedo	0.8±0.2[2][3]
Temperature	32±3 K
Apparent magnitude	21.9 (4.6 difference from primary's 17.3)[2]

Discovery

Namaka was discovered on 30 June 2005 and announced on 29 November 2005.^[4] It was nicknamed "Blitzen" by the discovery team before being assigned an official name.^{[citation needed]}

Physical characteristics

Namaka is only 1.5% as bright as its parent dwarf planet Haumea^[5] and is about 0.05% its mass. If it turns out to have a similar albedo, it would be about 170 km in diameter.^[2] Photometric observations indicate that its surface is made of water ice.^[5] Mutual events between 2009 and 2011^[6] were expected to improve the knowledge of the orbits and masses of the components of the Haumean system,^[3] but interpreting those observations was greatly complicated by the unexpected non-tidally locked spin state of Hiʻiaka, the larger moon. Namaka is similar in size to Makemake's moon MK2, despite being smaller. Further observations of Hiʻiaka might allow to determine its rotation period and spin state more precisely, at which point it should be possible to remove its effect from the data obtained in 2009.^[7][8]

See also

• Hiʻiaka, the other moon of Haumea