Overview

• Ammonite, officially designated 2023 KQ14, is the fourth known sednoid with an orbit stretching from 66 AU at perihelion to 252 AU at aphelion.
• Its discovery drew on archival infrared surveys, initial detections by Subaru Telescope, and confirmation by the Canada–France–Hawaii Telescope in July 2024, refining its orbital parameters.
• Simulations suggest Ammonite’s trajectory has remained stable for 4.5 billion years despite diverging from the clustered orbits of other sednoids.
• The misalignment of its orbital plane weakens support for the Planet Nine gravitational shepherding model and reduces confidence in finding a massive ninth planet.
• Researchers are now exploring alternative origins—including past stellar passages or the ejection of a former planet—and plan to test these theories with the Vera C. Rubin and Nancy Grace Roman observatories.