Ammonite: a Newly Discovered Distant Object that Hints at our Solar System's Past

The orbit of Ammonite (red line) and the orbits of the other three sednoids (white lines). Ammonite was discovered close to its perihelion, at a distance of 71 astronomical units (71 times the average distance between the Sun and Earth). The yellow point shows its position as of July 2025. (Credit: NAOJ)

July 15, 2025 -- An international research team that includes astronomers from ASIAA has used CFHT's MegaCam wide-field optical imager to trace out the orbit of a new distant object in our Solar System, named Ammonite. Initially discovered using the Subaru Telescope's wide-field prime-focus camera, Hyper Suprime-Cam (HSC), Ammonite was subsequently observed over a few nights during July 2024 at CFHT.

This newly discovered object is only the fourth Sednoid identified and its orbit helps understand what our Solar System looked like billions of years ago.

The object is currently designated 2023 KQ14. The team nicknamed the object Ammonite and a more classical name will be assigned later by the International Astronomical Union.

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The discovery was published in Nature Astronomy Discovery and dynamics of a Sedna-like object with a perihelion of 66 au

This international research is part of the Formation of the Outer Solar System: An Icy Legacy (FOSSIL) project. The team includes scientists from National Central University in Taiwan, NAOJ, Kinki University in Japan, the National Research Council of Canada, the Korea Astronomy and Space Science Institute, Nanjing University in China, and other institutions. Project members in Taiwan are supported by Academia Sinica and the National Science and Technology Council.

CFHT is located on Maunakea, land of the Kānaka Maoli people, and a mountain of considerable cultural, natural, and ecological significance to the Native Hawaiian people.

Media Contacts

  • Dr. Shiang-Yu Wang, Institute of Astronomy and Astrophysics, Academia Sinica sywang@asiaa.sinica.edu.tw (Tel) +886-2-2366-5338
  • Ms. Tsuey-Yin Piong, Media & Public Affairs, Secretariat, Academia Sinica (02) 2789-8821, fangzi@as.edu.tw
  • Ms. Steffi Tung Lin, Media & Public Affairs, Secretariat, Academia Sinica (02) 2789-8820, tunglin@as.edu.tw