Astronomers from the Harvard-Smithsonian Centre for Astrophysics have discovered a rare trans-Neptunian object called 2020 VN40
2020 VN40 is different from any other known object in the solar system as it moves in a synchronised rhythm with Neptune.
By discovering 2020 VN40, scientists have new insights into the dynamics of our solar system’s outermost regions.
A unique orbital pattern
2020 VN40 is the first known object to orbit the Sun once for every ten orbits completed by Neptune, making it a 1:10 orbital resonance. Resonances like this happen when two bodies influence each other gravitationally, despite vast distances. This rare orbital behaviour suggests that Neptune’s gravitational reach extends much farther than previously understood.
While many trans-Neptunian objects (TNOs) exist in similar resonances with Neptune, they typically reach their closest point to the Sun, called perihelion, when Neptune is on the opposite side of the solar system.
However, 2020 VN40 goes against this traditional pattern. From a bird’s-eye view of the solar system, it appears to approach the Sun when Neptune is nearby. In reality, the two are never actually close to each other because 2020 VN40’s orbit is tilted steeply compared to the flat plane of the solar system.
Exploring the distant edges
This discovery is part of the Large Inclination Distant Objects (LIDO) survey, which is a project that studies objects with unusual, highly tilted orbits in the outer solar system.
Using data from the Canada-France-Hawaii Telescope, along with follow-up observations from the Gemini Observatory and Magellan Baade Telescope, the LiDO team has been scanning the sky for elusive bodies in distant, unexplored regions.
The 2020 VN40 travels on an orbit that is approximately 140 times farther from the Sun than the Earth. On average. Its steeply inclined orbit distinguishes it from many other known TNOs, which tend to follow flatter paths.
Orbital dynamics
The unusual behaviour of 2020 VN40 challenges some existing assumptions about orbital dynamics in the solar system.
Most known objects in resonance with Neptune follow patterns that keep them out of close alignment with the planet when near the Sun. However, 2020 VN40’s alignment suggests a different kind of motion, previously unrecognised in solar system studies. This finding opens up the possibility that there may be many more objects following similarly unique orbits that haven’t yet been discovered.
These resonant and inclined orbits could reveal a great deal about how objects migrate and evolve. These paths may be remnants of a more chaotic, early phase of the solar system, when planets were still shifting and scattering small bodies.
Future discoveries
So far, the LiDO survey has revealed more than 140 distant objects, and astronomers expect many more to follow. With future observations from facilities like the Vera C. Rubin Observatory, scientists hope to discover even more unusual trans-Neptunian objects and learn how their orbits were shaped.
