Distant “Ammonite” Object Challenges “Planet Nine” Theory
New findings suggest a cosmic collision, not a hidden giant, shaped ancient orbits.
Astronomers tracking the far reaches of our solar system may need to rethink the elusive “Planet Nine.” A newly discovered object, nicknamed “Ammonite,” is forcing a re-evaluation of theories about a massive, unseen planet influencing distant orbits.
A Cosmic Fossil Emerges
Object 2023 KQ14, or “Ammonite,” has been classified as a Sednoid, a rare class of objects with highly eccentric orbits. Computer simulations indicate its path has remained stable for an astonishing 4.2 billion years, earning it the moniker “fossil of the solar system.” This ancient traveler provides a unique window into the early solar system’s history.
Discovered during the “Fossil” project, which studies the formation of the outer solar system, 2023 KQ14 was detected by the Subaru telescope in Hawaii. Subsequent observations with the Canada-France-Hawaii telescope and archival data allowed researchers to trace its orbit over 19 years. The findings were published in *Nature Astronomy*.
An Orbit Unlike Any Other
Measuring between 220 and 380 kilometers in diameter, 2023 KQ14 orbits the sun every 3,998 years. Its orbit spans from 66 to 438 astronomical units (AU) from the sun. During observation, it was located at 71 AU, more than double Neptune’s distance.
While 2023 KQ14 joins a select group of Sednoids, its orbit significantly diverges from the other three known members. Researchers believe that 4.2 billion years ago, these objects likely shared similar trajectories. However, the current stability and distinct path of 2023 KQ14 suggest a major disruptive event occurred approximately 400 million years after the solar system’s formation.
One hypothesis is that a massive planet, perhaps ejected from the solar system, caused these orbital shifts. This expelled body would have needed to be positioned much farther out than previously theorized.
A Visitor from Beyond?
An alternative explanation for the peculiar orbits of Sednoids, including 2023 KQ14, points to an external influence. Two studies published last year suggest that a star, roughly 0.8 times the mass of our sun, may have passed through the solar system billions of years ago.
Such close encounters are not uncommon in stellar nurseries where young solar systems develop. The gravitational pull of this passing star could have dramatically altered the paths of thousands of smaller celestial bodies, tilting their orbits around the sun.
This stellar encounter hypothesis also offers an explanation for the diverse types of moons orbiting the giant planets. Some transneptunian objects, flung inward by the passing star, could have been captured by Jupiter, Saturn, Uranus, and Neptune. This could account for the existence of both prograde moons, orbiting in the same direction as their planet, and retrograde moons, orbiting in the opposite direction.
While the “Planet Nine” theory, first proposed in 2016 by **Konstantin Batygin** and **Michael E. Brown** of Caltech, posited a gas giant ten times Earth’s mass, the discovery of 2023 KQ14 and the stellar encounter hypothesis present compelling alternative scenarios for the solar system’s most distant mysteries.
