On 17 September 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.

A team consisting of Mike Brown of Caltech, David Rabinowitz of Yale University, and Chad Trujillo of Gemini Observatory in Hawaii discovered Haumea on 28 December 2004, on images they had taken on 6 May 2004.

Ortiz later admitted he had accessed the Caltech observation logs but denied any wrongdoing, stating he was merely verifying whether they had discovered a new object.

However, the IAU announcement on 17 September 2008, that Haumea had been named by a dual committee established for bodies expected to be dwarf planets, did not mention a discoverer.

The location of discovery was listed as the Sierra Nevada Observatory of the Spanish team,[30][31] but the chosen name, Haumea, was the Caltech proposal.

Ortiz's team had proposed "Ataecina", the ancient Iberian goddess of spring;[27] as a chthonic deity, it would have been appropriate for a plutino, which Haumea was not.

Following guidelines established at the time by the IAU that classical Kuiper belt objects be given names of mythological beings associated with creation,[33] in September 2006 the Caltech team submitted formal names from Hawaiian mythology to the IAU for both (136108) 2003 EL61 and its moons, in order "to pay homage to the place where the satellites were discovered".

In addition, she is identified with Papa, the goddess of the earth and wife of Wākea (space),[35] which, at the time, seemed appropriate because Haumea was thought to be composed almost entirely of solid rock, without the thick ice mantle over a small rocky core typical of other known Kuiper belt objects.

[40] The symbol was designed by Denis Moskowitz, a software engineer in Massachusetts; it combines and simplifies Hawaiian petroglyphs meaning 'woman' and 'childbirth'.

[37][43][44] With a visual magnitude of 17.3,[23] Haumea is the third-brightest object in the Kuiper belt after Pluto and Makemake, and easily observable with a large amateur telescope.

If Haumea were in hydrostatic equilibrium and had a low density like Pluto, with a thick mantle of ice over a small rocky core, its rapid rotation would have elongated it to a greater extent than the fluctuations in its brightness allow.

Haumea's possible high density covered the values for silicate minerals such as olivine and pyroxene, which make up many of the rocky objects in the Solar System.

A thick ice mantle more typical of Kuiper belt objects may have been blasted off during the impact that formed the Haumean collisional family.

[45] Observations by the Spitzer Space Telescope gave a diameter of 1,150+250−100 km and an albedo of 0.84+0.1−0.2, from photometry at infrared wavelengths of 70 μm.

[11] The revised solution for Haumea's shape implies that it has a core of approximately 1,626 × 1,446 × 940 km, with a relatively high density of ≈ 2.68 g/cm3, indicative of a composition largely of hydrated silicates such as kaolinite.

[11] In 2005, the Gemini and Keck telescopes obtained spectra of Haumea which showed strong crystalline water ice features similar to the surface of Pluto's moon Charon.

[20] In addition, the structure of crystalline ice is unstable under the constant rain of cosmic rays and energetic particles from the Sun that strike trans-Neptunian objects.

Therefore, the spectra and colour suggest Haumea and its family members have undergone recent resurfacing that produced fresh ice.

[20] However, further studies of the visible and near infrared spectra suggest a homogeneous surface covered by an intimate 1:1 mixture of amorphous and crystalline ice, together with no more than 8% organics.

The absence of ammonia hydrate excludes cryovolcanism and the observations confirm that the collisional event must have happened more than 100 million years ago, in agreement with the dynamic studies.

[59] The absence of measurable methane in the spectra of Haumea is consistent with a warm collisional history that would have removed such volatiles,[20] in contrast to Makemake.

[68] Strong absorption features at 1.5 and 2 micrometres in the infrared spectrum are consistent with nearly pure crystalline water ice covering much of the surface.

[74] Observation of such transits would have provided precise information on the size and shape of Haumea and its moons,[75] as happened in the late 1980s with Pluto and Charon.

[78] However, in a situation unique among regular satellites, Namaka's orbit was being greatly torqued by Hiʻiaka, which preserved the viewing angle of Namaka–Haumea transits for several more years.

[79] Haumea is the largest member of its collisional family, a group of astronomical objects with similar physical and orbital characteristics thought to have formed when a larger progenitor was shattered by an impact.

In today's sparsely populated Kuiper belt, the chance of such a collision occurring over the age of the Solar System is less than 0.1 percent.

[85] Therefore, it appears likely that the dynamic scattered disc region, in which the possibility of such a collision is far higher, is the place of origin for the object that generated Haumea and its kin.

[85] Because it would have taken at least a billion years for the group to have diffused as far as it has, the collision which created the Haumea family is believed to have occurred very early in the Solar System's history.

[19] Joel Poncy and colleagues calculated that a flyby mission to Haumea could take 14.25 years using a gravity assist from Jupiter, based on a launch date of 25 September 2025.