Chariklo, a distant centaur asteroid measuring roughly 250 kilometers across and orbiting the sun between Saturn and Uranus, features an unexpected and changing system of two thin rings, according to measurements published in the journal Science Advances in 2026. The findings, gathered using the James Webb Space Telescope by a large research team led by authors including Santos-Sanz, reveal that the system’s rings are far more dynamic than previously understood in the otherwise sleepy outer solar system.
James Webb Telescope Detects Ring Changes
The James Webb Space Telescope captured rare glimpses of Chariklo's ring system by observing stellar occultations, where the asteroid and its rings pass in front of a distant background star. By measuring how much starlight the rings block, researchers can determine their density and transparency over time. Kofman noted that detecting the rings from Earth is extraordinarily difficult, comparing the scale to studying a washing machine on the moon or spotting a one-meter line on the lunar surface.
Why Outer Solar System Rings Are Surprising
Centaurs like Chariklo reside far from the sun’s warmth, completing one orbit every 62 Earth years. Because so little solar energy reaches this region, scientists previously assumed the outer solar system experienced very little activity or change. Kofman explained that researchers based in the inner solar system often misjudge the level of activity happening in the outer reaches. The newly documented shifts in Chariklo’s rings challenge the notion that these distant icy bodies remain completely static over time.
Potential Causes for Ring Instability
Researchers are still investigating the exact mechanisms driving the changes in Chariklo’s rings. According to the study, potential causes include bombardment by micrometeorites, interference from powerful magnetic forces, or gravitational disturbances from another small moon that orbits together with Chariklo. Kofman pointed out that centaurs frequently form binary systems where two rocks orbit one another. If the rings are composed of material stripped from a small accompanying moon by gravitational forces, studying them could provide scientists with direct clues about the composition of these objects.
Did you know? Chariklo was discovered to have rings in 2013, making it the very first asteroid known to possess a ring system.
Frequently Asked Questions
What is a centaur asteroid?
A centaur is a small icy body of rock and dust orbiting the sun—in Chariklo’s case, specifically between Saturn and Uranus—without entering the inner solar system like traditional comets do.
How do scientists measure asteroid rings from Earth?
Researchers measure distant rings using stellar occultation, capturing precise telescope data when an asteroid and its ring system pass directly in front of a background star to block and filter its light.
Who authored the new study on Chariklo?
The study was led by Santos-Sanz and published in the journal Science Advances in 2026, utilizing data gathered by the James Webb Space Telescope.
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