Astronomers announced the discovery of a new dwarf planet, provisionally named 2017 OF201, located in the remote outskirts of the solar system. The region far beyond Neptune's orbit was once thought to be largely empty, but the finding suggests it may be more populated than previously believed. According to Newsweek, a team led by Sihao Cheng from the Institute for Advanced Study identified this distant object, which is potentially large enough to be classified as a dwarf planet.
Measuring approximately 700 kilometers in diameter, 2017 OF201 is about three times smaller than Pluto and Eris, which are 2,377 kilometers and 2,326 kilometers across, respectively. The discovery was made possible through the analysis of astronomical image databases, including data from the Victor M. Blanco Telescope in Chile and the Canada-France-Hawaii Telescope in Hawaii.
"2017 OF201 spends only one percent of its orbital time close enough to us to be detectable," said Cheng, lead author of the study from the Institute for Advanced Study's School of Natural Sciences, as reported by Futurism. The object's extreme orbit takes it to a distance more than 1,600 times that of Earth's orbit from the Sun, reaching the Oort Cloud at the solar system's edge. This vast trajectory means it takes approximately 25,000 Earth years to complete a single orbit around the Sun.
The International Astronomical Union's Minor Planet Center confirmed the discovery on May 21, 2025, adding credibility to the findings, although the research has yet to undergo peer review.
Astronomers believe that the unusual orbit of 2017 OF201 indicates a complex history of gravitational interactions. "Perhaps its migration occurred in several stages. First, it was ejected into the Oort Cloud, the most distant region in our Solar System with many comets, and then was sent back," explained Eritas Yang, a member of the research team from Princeton University, according to ANSA. Additionally, Yang noted that the celestial body "must have undergone close encounters with a giant planet, causing it to be ejected far away on an extremely wide orbit."
The discovery challenges hypotheses about the outer reaches of the solar system. Researchers found that 2017 OF201 does not follow the same clustered orbital patterns observed in other trans-Neptunian objects. This finding could weaken the theory of a massive ninth planet influencing these distant bodies. "Many extreme trans-Neptunian objects have orbits that seem to cluster in specific orientations, but 2017 OF201 is an exception," said Jiaxuan Li, a coauthor and Princeton graduate student, as reported by ANSA.
Trans-Neptunian objects (TNOs), like 2017 OF201, vary in size, from large bodies like Pluto to smaller objects such as the 22-mile-wide Arrokoth. While further observations are needed to determine its exact dimensions, current estimates suggest that 2017 OF201 is among the largest known objects in such a distant orbit.
"The object's aphelion—the farthest point on the orbit from the Sun—is more than 1,600 times that of Earth's orbit. Meanwhile, its perihelion—the closest point on its orbit to the Sun—is 44.5 times that of Earth's orbit, similar to Pluto's orbit," Cheng explained, according to Newsweek.
"There could be another hundred objects with similar orbits and sizes; they are simply too far away to be detectable now," Cheng suggested, indicating the potential existence of "several hundred similar objects in similar orbits" in the Kuiper Belt.
"Even though advances in telescopes have allowed us to explore remote parts of the universe, there is still much to discover about our Solar System," Cheng said, as reported by Futurism.
Produced with the assistance of a news-analysis system.