Astronomers have uncovered a distant and icy world on the far edge of our Solar System — a frozen body so remote it takes roughly 25,000 years to complete just one orbit around the Sun. The discovery of 2017 OF201 is already reshaping how scientists see the Solar System’s outer frontier and challenging ideas about the mysterious, unseen forces lurking beyond Neptune.
A Record-Breaking Orbit
The new object, officially known as 2017 OF201, was identified using data collected between 2011 and 2018 from the Dark Energy Camera Legacy Survey (DECaLS) and the Canada-France-Hawaii Telescope (CFHT). After years of careful observation and orbital analysis, astronomers confirmed it as one of the most distant and extreme objects ever found within the Sun’s gravitational reach.
This frozen body follows an enormous, oval-shaped orbit that stretches from about 44.5 astronomical units (AU) at its closest point to a staggering 1,600 AU at its farthest. To put that in perspective, Neptune orbits just 30 AU from the Sun — meaning 2017 OF201 can wander more than 50 times farther out before swinging back again.
Because of this elongated path, it takes approximately 25,000 Earth years for the object to complete one full lap around the Sun. That means the last time it was near its current position, modern humans hadn’t yet developed agriculture.
A Distant, Icy Mystery
Researchers estimate 2017 OF201 to be about 700 kilometers wide, large enough to potentially classify it as a dwarf planet. Like Pluto and Eris, it likely consists of frozen rock and ice, locked in perpetual twilight on the edge of interstellar space.
Its orbit extends so far outward that it reaches into what scientists call the inner Oort Cloud — a vast, spherical shell of icy objects thought to be the Solar System’s last frontier. Few confirmed bodies have ever been found in this distant region, making 2017 OF201 an exciting clue in the search for our system’s outermost members.
Challenging the “Planet Nine” Hypothesis
The discovery also adds a surprising twist to the ongoing debate about Planet Nine — the hypothetical giant planet that some astronomers believe lies hidden far beyond Neptune.
According to Sihao Cheng and colleagues, who led the study, 2017 OF201’s orbit appears too stable to fit predictions that include Planet Nine’s gravitational influence. If such a massive planet were truly out there tugging on smaller objects, 2017 OF201’s long, unperturbed orbit would likely not exist in its current state.
This finding doesn’t necessarily disprove Planet Nine’s existence, but it does suggest that scientists may need to rethink its mass, location, or even whether it exists at all. Each new object discovered in the outer Solar System helps refine those models — and 2017 OF201 may be one of the strongest data points yet.
A Growing Map of the Solar System’s Edge
For decades, astronomers thought Pluto marked the edge of the Solar System. But discoveries in recent years — such as Sedna, Leleākūhonua, and now 2017 OF201 — have revealed a vast population of distant worlds orbiting in strange, stretched-out paths.
These discoveries suggest our Solar System is far larger and more complex than once imagined. Each icy body is like a time capsule from the early days of planetary formation, preserving information about how the Sun and planets came to be more than 4.5 billion years ago.
As telescopes grow more powerful and sky surveys become more detailed, astronomers expect to find hundreds or even thousands of similar trans-Neptunian objects (TNOs). Together, they may help fill in the missing pieces of how gravity, cosmic collisions, and distant interactions shaped the architecture of our cosmic neighborhood.
The discovery of 2017 OF201 isn’t just another icy rock — it’s a reminder that the Solar System is still full of unexplored worlds waiting to be found. Each new detection extends our cosmic map a little farther and deepens our understanding of the forces that hold it all together.
For now, 2017 OF201 will continue its silent journey through the darkness, drifting slowly along a 25,000-year path around our Sun a frozen witness to the Solar System’s deepest secrets.
Source:
Cheng, S. et al. (2025). Discovery of a dwarf planet candidate in an extremely wide orbit: 2017 OF201. arXiv.