Planetary science: The changing spin of Pluto’s moon, Charon (Nature Communications)
15 July 2026
Evidence for the slowing down of Charon’s spin-period (despinning) is recorded in the tectonic features on the surface of Pluto’s icy moon, according to a modelling study published in Nature Communications. The findings offer insights into the early thermal evolution of Charon and other icy satellites in the outer Solar System.
Objects across the solar system are thought to undergo a process called despinning, where tidal forces may slow a body’s rotation rate, altering its shape and temperature. Although the mechanism has long been theorised to occur on Charon, there has been a lack of clear geological evidence. Charon is a promising candidate for such evidence because its surface is around 4 billion years old and has experienced relatively limited resurfacing compared with other icy satellites.
Hanzhang Chen and colleagues examined variations in the orientations and types of tectonic features of mountain ranges in a region called Oz Terra, in Charon’s northern hemisphere. These features extend over 200 km and display asymmetric slopes consistent with compression, rather than extension. Modelling indicates the presence of an ice shell at least 30–36 km thick at the time of formation and suggests that the crust near the equator became approximately 1% shorter during this time, with this compression being absorbed along existing faultlines and creating the observed ridges. This modelling leads the authors to estimate that Charon’s early rotation period was approximately 14.3 hours, notably faster than its present tidally locked state of around 153.3 hours. This provides evidence to support a gradual slowing, or despinning, of its rotation.
These findings suggest that Charon may have begun its evolution in a relatively cold state, forming a thick, rigid ice shell early on. While uncertainties remain in modelling assumptions and stress estimates, the study provides a rare geological record of rotational evolution, with implications for understanding the thermal and orbital histories of other icy satellites.
- Article
- Open access
- Published: 14 July 2026
Chen, H., Moon, S. & Yin, A. Early tidal despinning history recorded in the tectonics of Oz Terra, Charon. Nat Commun 17, 5978 (2026). https://doi.org/10.1038/s41467-026-75069-7
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