Science & technology

Astronomers: Distant Object Identified as Potential Dwarf Planet

Published MAY 23 2025

Story

Above: Artist rendering of the proposed Planet Nine, an unconfirmed object that would explain a number of unusual orbits of trans-Neptunian bodies, created on July 19, 2015. Image credit: Tobias Roetsch/Contributor/Future Publishing via Getty Images

The Facts

In a discovery announced on Wednesday, astronomers from the Institute for Advanced Study identified a distant object named 2017 OF201, located approximately 90.5 astronomical units (AU) from Earth. Estimated at 700 km (435 miles) wide, the object is large enough to be considered a potential dwarf planet.
arXiv
arXiv
Institute for Advanced Study
2017 OF201 follows a highly elongated orbit lasting roughly 25,000 years, ranging from 44.5 AU at its closest approach to the Sun to over 1,600 AU — more than 1,600 times Earth’s orbital distance — at its farthest point in the inner Oort cloud.
New Scientist
Institute for Advanced Study
The International Astronomical Union's Minor Planet Center confirmed the discovery after researchers analyzed 19 observations captured over seven years using data from the Victor M. Blanco Telescope and Canada France Hawaii Telescope.
Institute for Advanced Study
ScienceAlert
Cosmic Log
Scientists identified 2017 OF201 using advanced algorithms to scan archival sky survey images, tracking subtle motions of light to identify the object. The discovery illustrates the use of open data in astronomical research.
Institute for Advanced Study
ScienceAlert
Cosmic Log
2017 OF201 is near Earth for only 1% of its orbit, making it difficult to observe. Its detection indicates that other distant objects beyond Neptune may remain undetected due to similarly remote and extended orbits.
New Scientist
ScienceAlert
Institute for Advanced Study
The orbital path of 2017 OF201 differs significantly from the pattern seen in other extreme trans-Neptunian objects, which have been studied in relation to a proposed ninth planet.
New Scientist
Earthsky
Bluesky Social

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The Spin

Narrative A

This discovery seriously undermines the "Planet Nine hypothesis" that's been floating around for years. Computer simulations show that if Planet Nine actually existed, it would gravitationally kick 2017 OF201 right out of the solar system within just 100 million years — but here it is, stable in its orbit. The object's trajectory doesn't follow the neat clustering pattern that supposedly proves Planet Nine's gravitational influence, making it a major outlier that the theory simply can't explain.

ScienceAlert

Narrative B

The clustering of extreme trans-Neptunian objects in specific orientations remains compelling evidence that a massive ninth planet lurks in the outer solar system, gravitationally shepherding these distant bodies into their observed patterns. Six known Kuiper Belt objects have elliptical orbits pointing in the same direction, and many orbit opposite to everything else in the solar system — clear signs of a nearby planet's gravitational pull that can't be easily dismissed by one anomalous object.

ABC News