Astronomers have identified a rare sednoid called Ammonite, an icy object beyond Neptune that offers new insight into the solar system’s early history.
Every once in a while, the outer solar system reminds us that we’ve only discovered a negligible portion of it, and that the vast majority is still full of surprises. The latest example of this is a trans-Neptunian object (TNO), first spotted by the Subaru Telescope in Hawaii in 2023.
Formally designated 2023 KQ14 by an international team of astronomers as part of the FOSSIL project (Formation of the Outer Solar System: An Icy Legacy), the object came to be known as «Ammonite.» But it’s neither a planet nor a dwarf planet. Instead, it belongs to a rare category of trans-Neptunian objects called sednoids.
At the closest point in its orbit (perihelion), Ammonite is about 66 astronomical units (AU) away from the sun (more than twice the perihelion of Neptune). One AU is the approximate distance from the sun to the Earth, about 93 million miles.
