[15] It was discovered on 19 October 2007 by American astronomers Megan Schwamb, Michael Brown, and David Rabinowitz at the Palomar Observatory in California[1] and measures approximately 600 kilometers (400 miles) in diameter.

This medium-sized TNO appears to be representative of a class of mid-sized objects under approximately 1000 km that have not collapsed into fully solid bodies.

Its 100-kilometer moon was discovered by Keith Noll, Will Grundy, and colleagues with the Hubble Space Telescope in 2008,[16][7][9][17] and named Gǃòʼé ǃHú.

Usually, when speaking English, the click consonants in words from Juǀʼhoan and other San languages are simply ignored (much as Xhosa is pronounced /ˈkoʊzə/ (KOH-zə) rather than [ǁʰosa]), resulting in /ˌɡuːnhoʊmˈdiːmə/ (GOON-hohm-DEE-mə) and /ˌɡoʊ.eɪˈhuː/ (GOH-ay-HOO) or /ˌɡoʊ.eɪˈkuː/ (GOH-ay-KOO).

[4] It has a bright absolute magnitude of 3.7,[2] and has been observed 178 times over 16 oppositions with precovery images back to August 1982.

Due to complications from its non-spherical shape, the rotational period cannot be definitely determined from current light-curve data, which has an amplitude of Δm = 0.03 ± 0.01 mag, but the simplest solution is 11.05 hours.

Grundy et al. propose that the low density and albedo of Gǃkúnǁʼhòmdímà, combined with the fact that TNOs both larger and smaller – including comets – have a substantial fraction of rock in their composition, indicate that objects such as Gǃkúnǁʼhòmdímà and 174567 Varda (in the size range of 400–1000 km, with albedos less than ≈0.2 and densities of ≈1.2 g/cm3 or less) retain a degree of porosity in their physical structure, having never collapsed and differentiated into planetary bodies like higher density or higher albedo (and thus presumably resurfaced) 90482 Orcus and 50000 Quaoar, or at best are only partially differentiated; such objects would never have been in hydrostatic equilibrium and would not be dwarf planets at present.