Science

Meet Ammonite: A Surprising New Object in Our Solar System!

2025-07-19

Author: Amelia

A New Discovery in the Solar System

The solar system just got a fascinating new addition! Astronomers have uncovered a unique object beyond Neptune and Pluto, sparking a re-evaluation of our understanding of cosmic history. This intriguing find, designated 2023 KQ14 and affectionately dubbed "Ammonite," has the potential to reshape everything we thought we knew about our celestial neighborhood.

Is Ammonite a Planet or Dwarf Planet?

Contrary to popular belief, Ammonite is neither a planet nor a dwarf planet like Pluto. Instead, it's classified as a sednoid, a category that also includes the dwarf planet candidate Sedna—discovered in 2003. Like its counterpart, Ammonite has a highly eccentric orbit far beyond Neptune, making it only the fourth sednoid identified so far.

How Big is Ammonite?

Estimates based on sunlight reflection suggest that Ammonite's diameter ranges from 137 to 236 miles (220 to 380 kilometers). While substantial, it's still smaller than Pluto, which boasts a diameter of approximately 1,477 miles (2,377 kilometers), and dwarfed by Earth’s 7,926 miles (12,756 kilometers).

Where is Ammonite Located?

Ammonite was detected an impressive 71 astronomical units (au) from the Sun—around twice the distance of Pluto. Its orbit is highly elongated, stretching as far as 432 au, taking an astonishing 4,000 Earth-years to complete just one revolution around the Sun.

What Does Ammonite Mean for the Planet Nine Hypothesis?

The discovery of Ammonite introduces new complications for the controversial Planet Nine theory. While many outer solar system bodies have similar elongated orbits that suggest they were influenced by an unseen planet, Ammonite's orbit contradicts this pattern, thus lowering the likelihood of Planet Nine's existence. Dr. Yukun Huang from the Center for Computational Astrophysics noted that Ammonite’s opposite trajectory among the sednoids raises intriguing questions about previously accepted theories.

Could Planet Nine Still Be Out There?

Despite the challenges posed by Ammonite, the elusive Planet Nine might still exist—possibly far beyond our current reach. It could even be a "ghost planet," ejected into the depths of space, leaving behind only the remnants of its gravitational effects. Alternatively, the unusual orbits might be the result of a stellar encounter billions of years ago.

How Was Ammonite Discovered?

The groundbreaking discovery of Ammonite was made with the Subaru Telescope in March 2023 as part of the FOSSIL project, dedicated to exploring the outer solar system. The naming reflects its ancient links to cephalopod fossils. Further observations were conducted in May and August, alongside archival analysis reaching back 19 years.

Why Call Ammonite a 'Fossil' of the Solar System?

Ammonite's classification as a 'fossil' stems from its age, estimated to be around 4.5 billion years—almost as old as the solar system itself. Studies suggest that Ammonite's orbit has remained stable throughout this time, offering a glimpse into the early configuration of our cosmic neighborhood.

The Significance of Ammonite's Discovery

The implications of finding Ammonite extend far beyond simply adding another object to our solar system. According to Dr. Shiang-Yu Wang, this discovery implies that significant forces shaped the outer solar system eons ago. Whether influenced by a passing star or a hidden planet, Ammonite brings us one step closer to unraveling the mysteries of our solar system's formation.

What’s Next for Ammonite?

The International Astronomical Union will eventually decide whether 2023 KQ14 will officially be named Ammonite. Nevertheless, astronomers will continue to push the boundaries of our solar system's exploration, hoping that clear skies and impressive technology will reveal even more cosmic wonders.