Astronomers Discover Rare Distant Object in Sync with Neptune

Released: 9th July, 2025, Academia Sinica Institute of Astronomy & Astrophysics (ASIAA), Taiwan 

Astronomers has discovered a rare object far beyond Neptune that moves in tandem with the giant planet. The object, designated 2020 VN40, is a trans-Neptunian object (TNO) orbiting the Sun in a 1:10 resonance with Neptune – meaning it completes one orbit around the Sun for every ten orbits that Neptune completes. This makes 2020 VN40 the first confirmed body known to share such a “ten-to-one” orbital rhythm with Neptune. Notably, the project leading to this discovery was initiated at Academia Sinica Institute of Astronomy & Astrophysics (ASIAA) by Dr. Rosemary Pike during her postdoctoral fellowship in Taiwan, and ASIAA contributed its allocated observing time on the Canada-France-Hawaii Telescope (CFHT) to the effort.

The discovery sheds new light on how objects in the outer Solar System behave and migrate. It supports the idea that many distant small bodies can be temporarily “captured” by Neptune’s gravity into simple orbital resonances as they drift through space. “This is a big step in understanding the outer Solar System,” said Dr. Rosemary Pike, lead researcher at the Center for Astrophysics | Harvard and 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.”

The discovery was made by the Large inclination Distant Objects (LiDO) survey, which searches for unusual distant objects on highly tilted orbits. The LiDO survey conducted wide-field observations using the CFHT on Maunakea for its main search, and employed Gemini North and the Magellan-Baade telescope for follow-up observations of particularly intriguing targets. By design, LiDO targets regions well above and below the plane of the planets (the ecliptic), an area of the outer Solar System that has been relatively unexplored. “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 at the University of Regina, a core member of the LiDO team. According to the team, 2020 VN40 orbits at an average distance about 140 times farther from the Sun than Earth, along a steeply inclined path around the Solar System.

What makes 2020 VN40 especially interesting is how its motion compares to Neptune’s. Typically, TNOs in simple resonances with Neptune always reach their closest point to the Sun (perihelion) when Neptune is far away, thereby avoiding close approaches. In contrast, 2020 VN40 comes to perihelion at nearly the same sector of the Solar System as Neptune when viewed from above. Because 2020 VN40’s orbit is so tilted, the two objects are never actually near each other in space – they only appear aligned in a flat projection – but this behavior is unique. All other known resonant TNOs orbit such that they avoid lining up with Neptune at perihelion, even in projection, making 2020 VN40 the first known exception to that rule.

“This discovery, which began with the planning and execution of CFHT observations at ASIAA, highlights how deep surveys of the distant Solar System can continue to challenge and refine our understanding of orbital dynamics,” said Dr. Ying-Tung Chen of ASIAA, a co-author of the study. “It is exciting to see how resonant objects like this one can reveal unexpected behaviors, and how international collaborations make such science possible.” 

These findings suggest that highly tilted orbits can lead to new and unexpected types of motion. The LiDO survey has already discovered over 140 distant objects, and more discoveries are expected from future projects. With next-generation facilities like the Vera C. Rubin Observatory on the horizon, scientists hope to find many more objects similar to 2020 VN40. 

“This is just the beginning,” said Dr. Kathryn Volk of the Planetary Science Institute. “We’re opening a new window into the Solar System’s past.”

More Information:

This research was presented in a paper "LiDO: Discovery of a 10:1 Resonator with a Novel Libration State" by Pike et al. (2025), The Planetary Science Journal.

The Gemini North telescope is one half of the International Gemini Observatory, which is funded in part by the U.S. National Science Foundation and operated by NSF’s NOIRLab.

Media Contact:

Dr. Rosemary E. Pike, rosemary.pike@cfa.harvard.edu  

Dr. Ying-Tung Chen, +886-2-2366-5356, ytchen@asiaa.sinica.edu.tw 

Dr. Mei-Yin Chou, +886-2-2366-5415, cmy@asiaa.sinica.edu.tw