Full Breakdown
JWST Observation Reveals Changing Rings Around Chariklo
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Background on Chariklo and Its Rings
Chariklo is a centaur-type body about 250 km (155 mi) across that orbits the Sun near 17 AU. In 2013 it became the first small Solar-System object beyond the giant planets known to possess rings, a discovery confirmed by occultations in 2014 and 2017. The system consists of two narrow, dense rings that were previously thought to be relatively stable.
Observation Details and Findings
The Institute of Astrophysics of Andalusia (IAA-CSIC) scheduled a stellar occultation for October 18 2022 using the James Webb Space Telescope at L2. The relative speed of Chariklo with respect to JWST was about 2.5 km s?¹, allowing fine spatial sampling.
Comparing the JWST data with earlier occultations showed opposite trends: the inner ring’s opacity increased, while the outer ring’s opacity decreased. The study, published on September 9 2026 in *Science Advances*, interprets these changes as evidence that the ring system is evolving on timescales of only a few years.
Data Summary
- Chariklo diameter: ~250 km (?155 mi)
- Observation date (scheduled): October 18 2022
- JWST distance from Earth: ~1.5 million km (L2)
- Relative motion during occultation: 2.5 km s?¹
- Images captured: 14,827 total; 1,646 used for analysis
- Ring opacity change: inner ring ?, outer ring ?
Official Statements & Responses
Pablo Santos-Sanz, lead author, said the results compel scientists to reconsider how small-body rings form, evolve, and remain stable. Yücel Kilic, co-author, highlighted the extraordinary precision required to predict the occultation, noting that accurate knowledge of Chariklo’s orbit, the background star’s position (from Gaia), and JWST’s trajectory were essential.
Verbatim Quotes
- “Our results force us to rethink how they form, how they evolve, and what mechanisms maintain their stability. The ability to detect these changes opens a new window for understanding the evolution of these systems and, possibly, that of other ring systems in the Solar System,” — Santos-Sanz.
Interpretation and Significance
The opacity variations suggest that rings around minor bodies are more active than previously believed. Possible explanations include material redistribution, changes in grain size or composition, or wavelength-dependent scattering introduced by JWST’s infrared filters. The findings challenge the view that rings around small objects are static.
Uncertainties and Open Questions
Researchers acknowledge that the exact mechanisms driving the opacity changes remain uncertain. The variations could reflect real physical evolution, differences in observational filters, or a combination of both. Additional occultation events, especially with JWST or other high-precision facilities, are needed to disentangle temporal evolution from wavelength effects.
Future Prospects
The study recommends scheduling more stellar occultations when Chariklo passes in front of a bright star. Continued collaboration between ground-based networks, Gaia astrometry, and space-based telescopes like JWST will be crucial for monitoring these dynamic ring systems.