229762 Gǃkúnǁʼhòmdímà
A mid-sized scattered disc object with a red moon and porous interior.
229762 Gǃkúnǁʼhòmdímà, originally designated 2007 UK126, is a large binary object in the scattered disc of the outer Solar System, considered a dwarf planet candidate. It was discovered on 19 October 2007 at Palomar Observatory by American astronomers Megan Schwamb, Michael Brown, and David Rabinowitz. The object is about 600 kilometers across, with a 100-kilometer moon named Gǃòʼé ǃHú, discovered in 2008 by Keith Noll, Will Grundy, and colleagues using the Hubble Space Telescope. Gǃkúnǁʼhòmdímà is representative of mid-sized trans-Neptunian objects under roughly 1000 kilometers that have not fully collapsed into solid bodies.
The name comes from the Juǀʼhoansi people of Namibia. In their mythology, Gǃkúnǁʼhòmdímà is an aardvark who defends her people using gǁámígǁàmì spines, hail, and her oryx horn. The name breaks down as gǃkún (aardvark), ǁʼhòm mà (young woman), and the feminine suffix dí. The moon’s name, Gǃòʼé ǃHú, means “oryx horn.” In English, the click consonants are typically dropped, so the primary name is often pronounced GOON-hohm-DEE-mə and the moon as GOH-ay-HOO or GOH-ay-KOO. ASCII renderings include ⟨G!kun||'homdima⟩ and ⟨G!o'e !Hu⟩. No planetary symbol was assigned to Gǃkúnǁʼhòmdímà, though an aardvark’s head has been used informally.
The object orbits the Sun at distances from 37.5 to 107.9 AU, taking about 620 years per orbit, with an eccentricity of 0.48 and an inclination of 23°. This eccentric orbit suggests gravitational scattering. Perihelion will occur in February 2046, and mutual occultation events with its moon will begin in late 2050. It has an absolute magnitude of 3.45 and has been observed 178 times over 16 oppositions, with precovery images dating back to August 1982. Both the Minor Planet Center and Johnston’s Archive classify it as a scattered disc object.
Stellar occultation data indicate an effective diameter of 600–670 kilometers, though the object is not spherical. Its rotational period is not firmly determined, but the simplest solution is 11.05 hours, likely between that and 41 hours. The system mass is about 1.36 × 10²⁰ kilograms, roughly 2% of Earth’s Moon and slightly more than Saturn’s moon Enceladus. Geometric albedo is about 0.15, and bulk density is roughly 1 gram per cubic centimeter. The moon likely makes up no more than 1% of the total mass.
Quick Facts
- Minorplanet
- yes
- Symbol
- (astrological)
- Background
- #C2E0FF
- Discoverer
- M. E. Schwamb / M. E. Brown / D. L. Rabinowitz
- Discovery Site
- Palomar Obs.
- Discovered
- 19 October 2007
- Earliest Precovery Date
- 16 August 1982
- Mpc Name
- (229762) Gǃkúnǁʼhòmdímà
- Named After
- Gǃkúnǁʼhòmdímà / (San mythology)
- Mp Category
- TNO / Scat-ext / SDO / distant
- Epoch
- 5 May 2025 (JD 2460800.5)
- Uncertainty
- 1
Facts from the source article.
Lore & Background
Gǃkúnǁʼhòmdímà was discovered on 19 October 2007 by American astronomers Megan Schwamb, Michael Brown, and David Rabinowitz at the Palomar Observatory in California. Its provisional designation 2007 UK126 was assigned by the Minor Planet Center on 26 February 2008, and it received the minor planet number 229762 on 31 December 2009. The International Astronomical Union officially named the object and its moon on 6 April 2019, drawing from Juǀʼhoansi mythology of Namibia: Gǃkúnǁʼhòmdímà is an aardvark defending her people, and the moon Gǃòʼé ǃHú means 'oryx horn'.
The object orbits the Sun at a distance of 37.5–107.9 AU once every 620 years and 2 months, with an eccentricity of 0.48 and an inclination of 23°. It belongs to the scattered disc, a population of TNOs with distant, eccentric, and inclined orbits influenced by Neptune. Its surface appears moderately red in visible light but drops in reflectance at near-infrared wavelengths, a trait shared with a few other TNOs. Near-infrared spectroscopy by the James Webb Space Telescope revealed water ice, carbon dioxide ice, carbon monoxide ice, and organic compounds (tholins) on its surface.
Stellar occultation events indicate an effective diameter of 600–670 km, but the object is not spherical. Its rotational period is uncertain, with a simplest solution of 11.05 hours but possibly up to 41 hours. The system mass is about 2% that of Earth's moon. Grundy et al. propose that its low density and albedo, combined with its size, indicate it has never collapsed into a fully solid body and is unlikely to be a dwarf planet.
Reader's Guide
Gǃkúnǁʼhòmdímà is significant as a representative of mid-sized trans-Neptunian objects (400–1000 km) that have not collapsed into fully solid bodies, retaining porosity in their structure. Its low density (about 1 g/cm³) and moderate albedo (0.15) contrast with higher-density or higher-albedo objects like Orcus and Quaoar, suggesting it never achieved hydrostatic equilibrium. The object's binary nature, with a red moon Gǃòʼé ǃHú discovered in 2008, provides insights into satellite formation and system dynamics. Its unusual surface composition—combining water ice, CO₂, CO, and tholins—places it among CO₂-type TNOs on dynamically excited orbits. The naming from Juǀʼhoansi mythology highlights cultural connections to the San peoples of Namibia. Its orbit, with perihelion in February 2046 and mutual occultation events beginning in late 2050, offers future observational opportunities. The object challenges simple classification of TNOs by color, as its visible and near-infrared properties do not fit neatly into standard categories.
Did You Know?
- Gǃkúnǁʼhòmdímà's name comes from Juǀʼhoansi mythology, where it appears as an aardvark defending her people with spines, hail, and an oryx horn.
- Its moon Gǃòʼé ǃHú is one of the reddest known TNOs and was discovered using the Hubble Space Telescope in 2008.
- The object has a bulk density of about 1 g/cm³, similar to that of water, indicating a porous interior.
- It will come to perihelion in February 2046, and mutual occultation events with its satellite will begin in late 2050.
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