Astronomers have discovered a mysterious object far beyond Neptune that orbits the Sun once for every ten Neptune orbits—an arrangement never seen before.
Known as 2020 VN40, the object’s orbit is dramatically tilted, and yet it remains locked in gravitational resonance with Neptune in a surprising, rhythmic pattern. Unlike other known trans-Neptunian objects, VN40’s closest approach to the Sun aligns visually with Neptune’s, though the two are not physically close. This odd configuration opens new questions about how the outer solar system formed and what other orbital surprises may be hiding in the distant dark.
A Rare Discovery in Neptune’s Shadow
Astronomers from the Center for Astrophysics | Harvard & Smithsonian have identified a rare object located far beyond Neptune, belonging to a group known as trans-Neptunian objects. Named 2020 VN40, it is the first confirmed case of an object that completes a single orbit around the Sun for every ten orbits made by Neptune, indicating a synchronized orbital pattern with the distant planet.
This unusual motion is helping researchers better understand the dynamics of the outer solar system and how objects in these distant regions might have arrived there. The finding also adds support to the idea that Neptune’s gravitational pull can temporarily trap passing objects as they drift through space.
Evolution of the Solar System
“This is a big step in understanding the outer solar system,” said Rosemary Pike, lead researcher from the Center for Astrophysics | Harvard & Smithsonian. “It shows that even very distant regions influenced by Neptune can contain objects, and it gives us new clues about how the solar system evolved.”
Details of the discovery were recently published in The Planetary Science Journal, a peer-reviewed publication of the American Astronomical Society.
The discovery was made by the Large inclination Distant Objects (LiDO) survey, which searched for unusual objects in the outer solar system. This survey utilized the Canada-France-Hawaii Telescope for its main survey operations, as well as Gemini Observatory and the Magellan Baade telescope for additional observations.
Exploring the Tilted Outskirts
The survey was designed to search for bodies with orbits that extend far above and below the plane of the Earth’s orbit around the sun, part of the outer solar system that hasn’t been well-studied.
“It has been fascinating to learn how many small bodies in the solar system exist on these very large, very tilted orbits,” said Dr. Samantha Lawler (University of Regina), a core member of the LiDO team. The object’s average distance is about 140 times farther from the sun than Earth and follows a very tilted path around the solar system.
An Orbital Oddity: 2020 VN40
What makes 2020 VN40 even more interesting is how it moves compared to Neptune. Most objects with a simple ratio of the duration of their orbit compared to the duration of Neptune’s orbit always come closest to the sun when Neptune is far away. In contrast, 2020 VN40 comes closest to the sun when Neptune is very close by, if you look at their positions from above the solar system.
The tilt of 2020 VN40’s orbit means that the objects are not actually close, because 2020 VN40 is actually far below the solar system- they only appear close when flattened onto a map. All other known resonant trans-Neptunian objects orbit such that they avoid this alignment at their closest approach to the sun, even in the flattened view.
A Strange Gravitational Dance
“This new motion is like finding a hidden rhythm in a song we thought we knew,” said Ruth Murray-Clay (University of California, Santa Cruz), co-author of the study. “It could change how we think about the way distant objects move.”
These findings suggest that highly tilted orbits can lead to new and unexpected types of motion. The LiDO survey has already found over 140 distant objects, and more discoveries are expected from future surveys. With telescopes like the Vera C. Rubin Observatory, scientists hope to find many more objects like 2020 VN40.
“This is just the beginning,” said Kathryn Volk of the Planetary Science Institute. “We’re opening a new window into the solar system’s past.”
Reference: “LiDO: Discovery of a 10:1 Resonator with a Novel Libration State” by Rosemary E. Pike, Ruth Murray-Clay, Kathryn Volk, Mike Alexandersen, Mark Comte, Samantha M. Lawler, Ying-Tung Chen, Arcelia Hermosillo Ruiz, Cameron Semenchuck, Cameron Collyer, J. J. Kavelaars and Lowell Peltier, 7 July 2025, The Planetary Science Journal.
DOI: 10.3847/PSJ/addd22
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