An object has been discovered orbiting the sun far beyond Pluto, calling into question theories about a possible Planet Nine in the solar system.
The object, for now, designated 2023 KQ14 and nicknamed “Ammonite,” was found by astronomers in Japan using its Subaru Telescope in Hawaii. Announced in a paper published today in Nature Astronomy, the object is not a planet but a sednoid. It’s only the fourth sednoid ever discovered.
Ammonite (2023 KQ14): What is A Sednoid?
A sednoid is an object beyond the orbit of Neptune that has a highly eccentric orbit, similar to that of the dwarf planet Sedna, one of the most distant objects in the solar system known to astronomers.
Astronomers use the distance between the Earth and the sun — one astronomical unit or au — to measure distance in the solar system. Sedna gets as close to the sun as about 76 au but as far away as 900 au on its elliptical orbit. 2023 KQ14 gets as close as 66 au from the sun and as far away as 252 au.
Ammonite (2023 KQ14) And The ‘Planet Nine’ Hypothesis
There has been a lot of attention among astronomers on Planet Nine in recent months. In May, scientists in Taiwan looking for a ninth planet in the solar system found hints in archive images. In June, a study by Rice University and the Planetary Science Institute put a number on the chances that a ninth planet exists — 40%.
The reason a ninth planet may exist is an unusual clustering of minor bodies in the Kuiper Belt — the outer solar system. Six objects — Sedna, 2012 VP113, 2004 VN112, 2010 GB174, 2013 RF98 and 2007 TG422 — all have highly elongated yet similarly oriented orbits. They appear to have been “herded” by the gravitational influence of a planet.
Why Ammonite (2023 KQ14) Might ‘Kill’ Planet Nine
The discovery of 2023 KQ14 may dent that theory because it follows an orbit different from the other sednoids. “The fact that 2023 KQ14’s current orbit does not align with those of the other three sednoids lowers the likelihood of the Planet Nine hypothesis,” said Dr. Yukun Huang of the National Astronomical Observatory of Japan, who conducted simulations of the orbit in a press release. “It is possible that a planet once existed in the Solar System but was later ejected, causing the unusual orbits we see today.” If a ninth planet does exist, it likely orbits even farther from the sun than supposed.
How Ammonite (2023 KQ14) Was Found
The object was found as part of the survey project FOSSIL (Formation of the Outer Solar System: An Icy Legacy), hence its nickname Ammonite. An ammonite is a fossil of a cephalopods that died out about 66 million years ago.
It was discovered in March, May, and August 2023 by Subaru and confirmed in July 2024 using the Canada-France-Hawaii Telescope. It was also found in archive images going back 19 years, which allowed astronomers to compute its orbit.
Wishing you clear skies and wide eyes.
