A New Perspective on the Age of Saturn’s Rings
A recent study, published in Nature Geoscience on December 16, 2024, reveals that Saturn's rings may be much older than previously thought.
NASA/JPL-Caltech/Space Science Institute
Publication date: 23/01/2025
Press, Research
Related teams :
Cosmochemistry, Astrophysics and Experimental Geophysics (CAGE)
Related themes : Origins
Dr. Ryuki HYODO, Chief Scientific Officer (CSO) at SpaceData Inc. and affiliated with the IPGP and Science Tokyo (University of Tokyo), in collaboration with Dr. Gustavo MADEIRA from IPGP and Université Paris Cité, as well as Dr. Hidenori GENDA from Science Tokyo, demonstrated that the formation of Saturn’s rings could date back much earlier than previously believed. Their water-ice-rich composition, almost devoid of dusty material is traditionally interpreted to be an argument proving they are much younger than the solar system and formed recently (maybe in the last 300 millions of years). But this new study shows that it a may actually be an illusion. This study, published in the international journal Nature Geoscience, challenges traditional hypotheses through theoretical models and numerical simulations. It shows that despite their bright appearance, devoid of dust, Saturn’s rings could be as old as the Solar System (about 4.5 billions of years).
For the first time, the team has proven that Saturn’s rings are highly resistant to contamination by exogenous micrometeoroids. This thermodynamic “cleaning” mechanism explains their “young” appearance while suggesting they may in fact date back to the formation of the Solar System, around 4.5 billion years ago. These findings upend the prevailing idea that Saturn’s rings are relatively recent, with an estimated age of only 400 million years.
This mechanism, illustrated in Figure 1, describes how micrometeoroids interact with Saturn’s rings. When a micrometeoroid collides with ring particles at a velocity of 20 km/s, the extreme impact causes the micrometeoroid to completely vaporize, forming a hot plasma at a temperature of around 10,000 degrees Celsius. This ionized material is then rapidly ejected due to Saturn’s magnetic field, either being pulled toward the planet itself or expelled outward beyond the rings. This process helps maintain the purity and brilliance of the rings by preventing the accumulation of foreign matter.
Micrometeoroid bombardment consists of tiny dust particles, primarily composed of carbon and silicates, originating from outside Saturn’s system, such as the Kuiper Belt. These particles were once thought to accumulate progressively on celestial objects, including Saturn’s rings, leading to their darkening and an increase in non-icy components.
However, observations from the Cassini spacecraft (NASA-ESA) revealed that Saturn’s rings are composed of more than 99% water ice. This composition led to studies in the 2010s–2020s that estimated their age to be no more than 400 million years, based on the time required for such “dust” to accumulate. Recent findings challenge this method.
The study identifies mechanisms that prevent micrometeoroids from accumulating on Saturn’s rings. These mechanisms suggest the rings could be as old as the Solar System itself. These results emphasize that evaluating the rings’ age based only their appearance, that is the abundance of dusty material in the ring only, can be misleading, significantly altering our understanding of their origin and evolution.
This study establishes a new framework for rethinking the evolution of Saturn’s rings and the formation processes of ring systems around other planets. Understanding when and how these massive structures formed could enrich our knowledge of the Solar System’s history while providing insights into Earth’s evolution as a habitable planet.
Contact Information:
Authors of the article:
– Dr Gustavo MADEIRA, IPGP :
– Dr Ryuki HYODO :
For comments and perspectives:
– Pr Sébastien CHARNOZ, IPGP et Université Paris Cité :
