Astronomers using the Subaru Telescope in Hawai‘i have discovered a distant celestial object lurking in the outer edges of the Solar System. Named 2023 KQ14—and nicknamed “Ammonite object” due to its coiled orbit and resemblance to ancient marine fossils—this newly identified body is located as far as 252 astronomical units (AU) from the Sun. For comparison, Pluto orbits at an average distance of just 40 AU.
Estimated to be between 220 and 380 kilometers in diameter, the Ammonite object belongs to an elite group of remote bodies known as sednoids, characterized by their extremely elongated and stable orbits that suggest minimal interaction with Neptune’s gravity. Simulations suggest Ammonite has been on this unusual path for approximately 4.5 billion years, providing a rare glimpse into the Solar System’s early architecture.
Impacts on the Planet Nine Hypothesis
The discovery of the Ammonite object is reshaping discussions around the elusive Planet Nine, a hypothetical massive planet believed by some astronomers to exist beyond Neptune. This theory was largely built on the observation that several extreme trans-Neptunian objects (ETNOs) exhibit similar orbital clustering, possibly due to the gravitational pull of a hidden ninth planet.
However, Ammonite’s orbit stands out. Unlike other sednoids such as Sedna or 2012 VP113, its trajectory does not align with the predicted patterns that would be influenced by a single distant planet. Simulations led by Yukun Huang and the team at Japan’s National Astronomical Observatory reveal that Ammonite’s orbit diverges significantly, challenging the gravitational clustering expected if Planet Nine were exerting its pull.
As project lead Fumi Yoshida notes, the Ammonite object is too far from Neptune to have been disturbed by its gravity, suggesting that its orbit was likely sculpted by a yet-unknown process or event in the early Solar System.
Rethinking the Outer Solar System
Ammonite’s unusual orbital signature is forcing scientists to revisit existing planetary models. If Planet Nine does exist, it might be located much farther away or possess an orbit different from earlier predictions. Conversely, some researchers argue that the alignment seen among sednoids could be the result of observational bias, as only the most detectable orbits are being found.
The findings were published in Nature Astronomy, sparking renewed interest in mapping the farthest frontiers of our Solar System. As astronomers continue scanning the sky through ground-based telescopes and missions like NEOWISE, the hope is that additional ETNOs will help settle the debate, either by confirming the existence of Planet Nine or forcing a complete rethink of deep space mechanics.
Whether the Ammonite object turns out to be an anomaly or a new cosmic clue, its discovery marks a pivotal moment in our understanding of the Solar System’s distant past and possible hidden worlds that still await detection.
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