Astronomers Discover Ancient Cosmic 'Fossil' at Solar System’s Edge — A Blow to Planet Nine Theory?

Astronomers have discovered a mysterious celestial object outside of Pluto's orbit. This discovery, known as a "cosmic fossil," may cast doubt on one of the most hotly contested hypotheses in astronomy: the existence of the elusive Planet Nine.

Known by its nickname "Ammonite" and official designation 2023 KQ14, the object was discovered while using Hawaii's Subaru Telescope for the Formation of the Outer Solar System: An Icy Legacy (FOSSIL) study. at addition to joining the ultra-rare class of distant solar system planets known as sednoids, it might make scientists reevaluate what is—or is not—found at the furthest limits of our cosmic neighbourhood.

What Is So Unique About 2023 KQ14?

The orbit of KQ14 in 2023 is not like that of other known solar system objects. Its perihelion, or closest point to the sun, is an astounding 71 times farther from the sun compared to Earth's distance. Up to 45 times taller than Mount Everest, the item is just the fourth documented sednoid to date and ranges in width from 220 to 380 kilometres.

Its orbit, however, differs from that of the other three sednoids that have been found, which is fascinating. This discrepancy casts major doubt on the Planet Nine theory, which postulates that the peculiar orbits of such objects are caused by the gravitational attraction of a massive, hidden planet.

Yukun Huang, principal researcher from Japan's National Astronomical Observatory, stated, "The likelihood of the Planet Nine hypothesis is reduced because the current orbit of 2023 KQ14 does not align with those of the other three sednoids."

"It is possible that a planet once existed in the solar system but was later ejected, causing the unusual orbits we see today."

Following a 4.5-Billion-Year Path

Computer calculations indicate that, despite its peculiar current trajectory, ammonite's orbit has been steady for 4.5 billion years—nearly as long as the solar system itself. All four of the sednoids may have had comparable orbits about 4.2 billion years ago, according to the FOSSIL team, suggesting that a significant gravitational disruption took place about 400 million years into the formation of the solar system.

The initial sighting of the object occurred in 2023 during observations in March, May, and August. Researchers used the Canada-France-Hawaii Telescope to confirm it again in July 2024, and they then tracked its whereabouts using 19 years' worth of historical data.

How Will This Affect Planet Nine?

A massive, secret planet that lurks far beyond Neptune and shapes the orbits of faraway entities like sednoids has been the subject of the Planet Nine idea since it was first put forth in 2016. However, the independent path of KQ14 for 2023 suggests that this may not be the case. Rather, researchers hypothesise that these "fossils" were left behind when a former planet was destroyed early in the solar system's history, upsetting neighbouring orbits.

"Objects with long orbits and long perihelion distances suggest that something extraordinary happened in the early history of our solar system," said planetary scientist and research co-author Fumi Yoshida.

Looking Ahead: More Clues, More Fossils

One of the few observatories on Earth that can detect such weak, far-off planets is the Subaru Telescope, whose exceptional power is demonstrated by the finding of 2023 KQ14. Scientists are hoping to find a lot more sednoids to solve the long-standing mystery of the turbulent early years of our solar system.

"I would be happy if the FOSSIL team could make many more discoveries like this one and help draw a complete picture of the solar system's history," Yoshida stated.