Astronomers have discovered a strange and distant object orbiting far beyond Neptune, raising new questions about the outer edges of our solar system.
The object, called 2017 OF201, is a type of icy body known as a trans-Neptunian object (TNO).
It may be large enough to be classified as a dwarf planet—similar to Pluto.
The discovery was led by Sihao Cheng of the Institute for Advanced Study, alongside colleagues Jiaxuan Li and Eritas Yang from Princeton University.
Their findings were announced on May 21, 2025, by the International Astronomical Union’s Minor Planet Center and shared as a preprint online.
What makes 2017 OF201 so intriguing is its unusual orbit.
It travels incredibly far from the sun—at its most distant point, it is over 1,600 times farther from the sun than Earth is. Even at its closest, it is still about 44 times farther than Earth, putting it on a similar path to Pluto. The full orbit takes roughly 25,000 years to complete.
Scientists believe such an extreme orbit means the object was pushed and pulled by the gravity of giant planets like Jupiter or Neptune long ago. It might have even been flung out to the distant Oort Cloud—a region of icy bodies surrounding the solar system—and then drifted back inward.
Interestingly, many distant TNOs seem to follow similar orbital paths, which has led some scientists to suspect the influence of an unseen ninth planet, often called Planet X or Planet Nine. But 2017 OF201 doesn’t follow this pattern. That makes it a possible outlier that could challenge the idea that Planet Nine exists.
The research team estimates the object is around 700 kilometers wide, making it the second largest known object with such a far-reaching orbit. For comparison, Pluto is more than three times as wide. The exact size of 2017 OF201 still needs to be confirmed, and researchers hope future radio telescope observations can help.
The object was found by analyzing old data from telescopes in Chile and Hawaii, using a computer program designed by Cheng. It looked for small bright dots that moved in a way consistent with a faraway object in orbit. The team spotted 2017 OF201 in 19 different images taken over a seven-year period.
Because 2017 OF201 is only visible from Earth for about 1% of its orbit, its detection suggests that many similar objects may be out there, still waiting to be found.
This surprising find shows that the region beyond Pluto isn’t as empty as once thought—and that we still have much to learn about our own solar system.
Source: KSR.
