2023 KQ14
, informally nicknamed Ammonite, is a trans-Neptunian object orbiting the Sun on an extremely wide elliptical orbit. It was discovered by the Subaru Telescope atop Mauna Kea on 16 May 2023, as part of an internationally led astronomical survey known as the "Formation of the Outer Solar System: an Icy Legacy" survey. is unusual because the direction of its orbital apsides is not aligned with those of previously known TNOs with high-perihelion elliptical orbits, which challenges the hypothesis that an unseen distant planet could be aligning their orbits. likely has a diameter between.
Discovery
was discovered by the 8.2-meter Subaru Telescope at Mauna Kea Observatory, Hawaii, on 16 May 2023, during the operation of the "Formation of the Outer Solar System: an Icy Legacy" astronomical survey. The FOSSIL survey, which is an international collaboration of astronomers primarily from Japan and Taiwan, began in 2020 with the initial goal of detecting faint Jupiter trojans and trans-Neptunian objects across the sky. The survey discovered during the first year of its second phase, when it began focusing on detecting TNOs only.Astronomers of the FOSSIL survey identified in FOSSIL observations from March to August 2023 and noticed that it was extraordinarily far from the Sun. To better determine 's orbit and distance, astronomers Ying-Tung Chen and John J. Kavelaars reobserved the object with the Canada–France–Hawaii Telescope in July 2024. These extra observations allowed Chen to precover in archival Dark Energy Camera images from June 2021 and May 2014. The discovery of the object was announced by the Minor Planet Center on 14 April 2025, and a research paper detailing the discovery was published in Nature Astronomy on 14 July 2025.
Name
The 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 its discovery date. The object was unofficially nicknamed "Ammonite" by the FOSSIL team, after the ammonite fossil which serves as an analogy to the object's fossilized orbit since the beginning of the Solar System. An official name can be given once is given a permanent minor planet catalog number by the MPC.Orbit
follows an extremely wide elliptical orbit around the Sun, whose distance with respect to the Solar System barycenter ranges from 65.9 astronomical units at perihelion to at aphelion. It takes roughly 4,000 years for to complete one orbit. 's barycentric orbit has a semi-major axis of, eccentricity of 0.739, and an inclination of 11° with respect to the ecliptic. was away from the Sun when it was discovered, and it will pass perihelion in February 2063.is one of the four known distant TNOs whose perihelion distances are greater than q = and whose semi-major axes are greater than a =. These TNOs are sometimes known as sednoids. has the third farthest perihelion among the known TNOs, following and . is far enough away from Neptune that its orbit is barely affected by the planet's gravity. Because is detached from the gravitational influence of the known planets, its orbit is dynamically stable for billions of years and had likely remained unchanged since the beginning of the Solar System 4.5 billion years ago. This suggests that external gravitational influences must be responsible for forming the orbits of and the sednoids—possible sources include a passing rogue star or planet, a distant unseen planet, migration of the Sun through different parts of the Milky Way, or other stars in the Sun's birth cluster.
Orbital alignment
The direction of 's orbital apsides, or longitude of perihelion, is not aligned with those of the three previously known sednoids. Whereas the orbits of the three previously known sednoids appear to cluster between ϖ = 0° and ϖ = 90°, the orbit of points in the opposite direction at ϖ = 271°. The anti-aligned orbit of challenges but does not rule out the Planet Nine hypothesis, which was originally proposed to explain the apparent orbital clustering of the three previously known sednoids. If Planet Nine exists, then it should orbit the Sun at a farther distance in order to keep the orbit of stable for at least one billion years.Simulations without Planet Nine by Ying-Tung Chen and collaborators in 2025 suggested that there is a 97% chance that 's orbit was previously aligned with the three known sednoids 4.2 billion years ago, or roughly 300 million years after the formation of the Solar System, if the orbits of all sednoids were apsidally precessing due to perturbations by the giant planets. This primordial cluster of aligned orbits would have then gradually dispersed due to the sednoids' differing apsidal precession rates. In this case, this would suggest that the sednoids' orbits were perturbed by a passing rogue planet early in the Solar System's history.