Meet “Ammonite” – Fossil World at Solar System’s Edge Challenges Planet Nine Theory
Ammonite is the informal name for the trans-Neptunian object 2023 KQ14, discovered by the FOSSIL survey with Subaru’s 8.2-meter telescope in early 2023. Follow-up observations in July 2024 with the Canada–France–Hawaii Telescope and archival data from 2005 extended its observational arc to 19 years. Ammonite is a sednoid, a distant trans-Neptunian object with a highly eccentric orbit (e ≈ 0.74) and a diameter estimated at 220–380 km. Its orbital direction is markedly different from the three previously known sednoids, breaking their apparent clustering. Backward and forward simulations show Ammonite has been on a stable solar orbit for at least 4.5