90568 Goibniu
90568 Goibniu is a large trans-Neptunian object that was discovered in 2004 by the Near-Earth Asteroid Tracking survey at Palomar Observatory. It is classified as a classical [Kuiper belt object] of the dynamically "hot" population, which follow highly inclined or eccentric orbits around the Sun.
Goibniu is in diameter, according to measurements of its infrared thermal emission by the Herschel and Spitzer space telescopes. It shows small variations in brightness over its 5.86-hour rotation period. Some astronomers have suggested that Goibniu is large enough that it could be a dwarf planet. However, the shape of Goibniu is unknown–it could either be a spheroid with small albedo spots or an ellipsoid whose rotation axis is pointed towards Earth. Furthermore, its low albedo suggests it has never been resurfaced and thus is unlikely to have the planetary geology thought to be typical of dwarf planets.
History
Discovery
Goibniu was discovered on 13 April 2004 by the Near-Earth Asteroid Tracking survey, which was a NASA-directed project for finding near-Earth asteroids in the sky using telescopes at various observatories across the United States. The telescope that discovered Goibniu was the Samuel Oschin telescope at Palomar Observatory in San Diego County, California. The people involved in making the discovery observations at Palomar included Steven Pravdo, D. MacDonald, Kenneth Lawrence and Michael D. Hicks. The discovery of Goibniu was announced by the Minor Planet Center on 14 April 2004, after several other observatories observed the object.Precovery observations of Goibniu were first reported by astronomer Reiner Stoss and published by the MPC on 10 June 2004. These precovery observations, which came from Digitized Sky Survey images from 1993–1997, allowed for an accurate determination of Goibniu's orbit without the need for follow-up observations. Even earlier precovery observations have since been reported, from dates as early as December 1954.
Number and name
This object has the minor planet provisional designation, which was given by the MPC in the discovery announcement. The provisional designation indicates the year and half-month of the object's discovery date. received its permanent minor planet catalog number of 90568 from the MPC on 30 August 2004.Until 2025, did not have a proper name and the discoverers' privilege for naming this object expired ten years after it was numbered. According to naming guidelines by the International Astronomical Union's Working Group for Small Bodies Nomenclature, was open for name suggestions that relate to creation myths, as recommended for Kuiper belt objects in general. On 1 September 2025, it was officially named Goibniu, after the Irish god of metallurgy and hospitality.
Orbit
Goibniu is a trans-Neptunian object orbiting the Sun at a semi-major axis or average distance of 41.9 astronomical units. It has an orbital eccentricity of 0.08 and an inclination of 22° with respect to the ecliptic. In its 271-year-long orbit, Goibniu comes as close as 38.7 AU from the Sun at perihelion and as far as 45.2 AU from the Sun at aphelion.Goibniu is located in the classical region of the Kuiper belt 39–48 AU from the Sun, and is thus classified as a classical Kuiper belt object. The high orbital inclination of Goibniu makes it a dynamically "hot" member of the classical Kuiper belt. The hot classical Kuiper belt objects are believed to have been scattered by Neptune's gravitational influence during the Solar System's early history.