In the dark confines of the solar system, beyond the orbit of Neptune, a new world has appeared. First detected in May 2023 from the top of the Mauna Kea volcano in Hawaii, astronomers have recently assigned it the name \u00a0Ammonite\u00a0. However, the discovery brings mixed news, particularly for those hoping to find the elusive \u00a0Planet Nine\u00a0.<\/p>\n
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Short Overview of Ammonite<\/strong>. 2023 KQ14, or \u201cAmmonite,\u201d is a \u00a0trans-Neptunian object\u00a0 measuring between 220 and 380 km in diameter. It orbits the sun in an extremely wide \u00a0elliptical path\u00a0. A unique aspect of its orbit is its misalignment with other similar objects. According to a study published in Nature Astronomy<\/a>, this finding challenges the hypothesis that a distant planet\u2014speculated to be “Planet Nine”\u2014could be influencing the trajectory of celestial bodies in this region.<\/p>\n <\/p>\n A True Cosmic Fossil<\/strong>. The nickname “Ammonite,” akin to ancient marine fossils, is fitting. Astronomers believe this object is a relic of our solar system, a \u00a0time capsule\u00a0 whose orbit has remained virtually unchanged for \u00a04.5 billion years\u00a0.<\/p>\n <\/p>\n Its discovery was made possible thanks to the Fossil II Project<\/a> (Formation of the Outer Solar System: An iory legacy), which tracked such objects using the Subaru telescope in Hawaii. The team found more than they anticipated; Ammonite is undeniably \u00a0special\u00a0.<\/p>\n <\/p>\n An Exclusive Club of Celestial Bodies<\/strong>. In addition to its substantial size, Ammonite is located at an impressive distance. It has the \u00a0third-most distant perihelion\u00a0 ever detected, with its closest point to the sun at \u00a066 astronomical units\u00a0\u2014more than twice the distance of Neptune. Notably, astronomers identify this area as the ”\u00a0perihelium gap\u00a0,” between 50 and 75 astronomical units, where such objects were previously \u00a0unidentified\u00a0.<\/p>\n <\/p>\n Ammonite is classified as a \u00a0sedoid\u00a0, joining an ultra-exclusive group of trans-Neptunian objects. Prior to this discovery, only three such objects were known: \u00a0Sedna\u00a0 (a candidate for a dwarf planet), \u00a02012 VP113\u00a0, and \u00a0Lele\u0101k\u016bhonua\u00a0. These celestial bodies are unique due to their enormous and highly elliptical orbits, with their closest points to the sun being so remote that the gravity of Neptune has minimal effect on them. They are, in essence, \u00a0gravitationally isolated\u00a0.<\/p>\n <\/p>\n Implications for the Planet Nine Hypothesis<\/strong>. For years, the idea of Planet Nine has garnered attention to explain an unusual anomaly: the orbits of sedoids and other extreme trans-Neptunian objects appear to be clustered, as if a massive, unseen planet exerted gravitational influence over them.<\/p>\n <\/p>\n However, Ammonite’s orbit does not align with this theory. In fact, it points in the \u00a0opposite direction\u00a0 of those other three sedoids. Based on many proposed models for Planet Nine, Ammonite’s orbit would be unstable; it could not have remained in its current trajectory without being ejected from the solar system long ago.<\/p>\n <\/p>\n