James Webb has revealed unexpected changes in Chariklo’s two rings, which appear to be evolving in opposite ways over only a few years.

For much of modern astronomy, rings were believed to belong only to the giant planets of the Solar System, including Jupiter, Saturn, Uranus, and Neptune. That assumption changed in 2013, when astronomers discovered two dense rings around Chariklo, a small body only about 250 kilometers across that travels between Saturn and Uranus at nearly 17 times the Earth-Sun distance.

On October 18, 2022, researchers led by the Institute of Astrophysics of Andalusia (IAA-CSIC) used the James Webb Space Telescope (JWST) to examine Chariklo’s rings during a stellar occultation. This method tracks how a star’s light dims as an object passes in front of it. A new study published in Science Advances, also led by the IAA-CSIC, now shows for the first time that Chariklo’s rings can change measurably over the course of only a few years.