There is a new member in the Solar System: a transnettunian object – 2017 of201 – with such an extensive orbit that takes 25,000 years to be completed.
A small group of researchers from the Institute for Advanced Study has identified a celestial object of great interest beyond the planets of the Solar System. It is 2017 of201a transnettunian object (tno) potentially classifiable as a dwarf planet, comparable – by size and orbit – to the most famous Pluto.
Identified object. The discovery was led by Sihao Cheng, together with Martin A. and Helen Choljian of the School of Natural Sciences, with the contribution of colleagues Jiaxuan Li and Eritas Yang of the University of Princeton. The team used advanced computational algorithms to analyze archive images from Victor M. Blanco and Canada-France-Hawaii telescopes (CFHT), identifying the new object in 19 exhibitions collected over seven years. The Minor Planet Center of the International Astronomical Union made official the discovery on May 21, 2025, and the team shared the results in a preprint on Arxiv.
Record orbit. What makes it unique 2017 of201 It is not only the distance to which it is located, but above all its extreme orbit: Perieliothe closest point, is located at 44.5 astronomical units (ua = at the land-sell distance), a distance similar to that of Pluto; the apheliumthe farthest point, instead exceeds 1600 UA, making it his orbit one of the most extensive known.
The complete cycle around the sun takes about 25 thousand years. “Such a large orbit implies that the object has undergone strong gravitational disturbances, probably from a close encounter with one or more giant planets,” explains Yang. Cheng even hypothesizes that the object may have been thrown into the “cloud of oort”, the remote region populated by comets, and then pushed again towards the inside of the Solar System.
Anomaly that challenges the planet nine. Many extremes seem to have orbits grouped in similar guidelines, a phenomenon that has led some astronomers to hypothesize the existence of a hypothetical planet nine, capable of gravitating these bodies gravitating. However, 2017 of201 It stands out from this scheme, suggesting that the framework can be more complex than expected. “Perhaps a single giant planet has not been enough to have brought him to his current orbit And therefore there are still many things to explain », observes them.
How big is it? According to initial estimates, 2017 of201 has a diameter of about 700 kilometerswhich would make it the second largest object discovered in such a remote orbit, after Pluto (2,377 km). However, further observations are needed, potentially with RadioTelescopi, to precisely determine their size and physical characteristics.
A region far from empty. Traditionally, the space beyond the Kuiper belt has been considered a relatively deserted area. But 2017 of201 tells another story.
“He only spends 1% of his time close enough to be observed with our current tools,” explains Cheng, “The fact that we managed to identify it suggests that there could be hundreds of similar objects out there, simply too far away to be detected».
Open Science. One of the most remarkable aspects of the discovery is that it was made entirely with public archive data.
“Anyone could have found this object», Underlines them. «With the right tools and a good preparation, even non -professional students or scientists could have made this discovery. It is a perfect example of the value of sharing scientific resources ».
