Astronomers using the Subaru Telescope have made a groundbreaking discovery, uncovering a small body beyond Pluto that challenges our understanding of the outer Solar System. The object, designated 2023 KQ14, was discovered as part of a survey project called FOSSIL and has implications for the formation, evolution, and current structure of the system.
Found in March, May, and August 2023, 2023 KQ14 is a “sednoid,” a rare type of object that takes on an unusual orbit. While its path differs from other sednoids, simulations suggest it has maintained a stable orbit for at least 4.5 billion years. This discovery reveals the outer Solar System to be more diverse and complex than previously thought.
The finding also puts new constraints on the hypothetical Planet Nine. If it exists, its orbit must lie farther out than predicted. Dr. Yukun Huang notes that the sednoid’s unusual orbit makes it unlikely for Planet Nine to exist. Instead, a planet may have been ejected from the system in the distant past.
The discovery was made possible by observations taken with the Subaru Telescope and subsequent follow-up studies using other telescopes. The object’s unique location, far from Neptune’s gravitational influence, suggests that something extraordinary occurred during its formation. Further study is needed to understand the orbital evolution and physical properties of this “fossil” from the early Solar System.
Source: https://www.nao.ac.jp/en/news/science/2025/20250715-subaru.html