In June 2013, seven telescopes across South America were trained on the star UCAC4 248-108672, in anticipation of it being occulted by the centaur Chariklo. (Centaurs are a unique class of large asteroids that have properties of both asteroids and comets.) To researchers’ surprise, they witnessed not only the occultation, but additional brief dips in the star’s light, before and after the centaur passed in front of it. From these observations, scientists concluded that Chariklo has two rings. It was the first discovery of rings around an asteroid, and was announced to the public on March 26, 2014, concurrent with the research’s publication in Nature.
Further research since has provided more details, including the rings’ remarkable stability around an object that has frequent gravitational encounters with planets. Occultation observations between 2013-2020 helped refine the centaur’s size and shape, and in 2022, the James Webb Space Telescope detected water-ice in the rings. Researchers have also detected rings around a second centaur, Chiron, though understanding of their nature is still evolving.
