Webb Observes Chariklo, a Weird Ringed Object in the Solar System

The ringed object, dubbed 10199 Chariklo, or just Chariklo for short, is a minor planet centaur and the only such body to have rings orbiting it.


Of all the ringed worlds in the solar system, with Saturn being the most famous, you have probably never heard about Chariklo. This celestial body is the largest confirmed centaur. Centaurs are cosmic bodies of our solar system that have either a perihelion or a semi-major axis that transits them between those of the outer planets, Jupiter and Neptune. Chariklo is the largest such body. While these bodies usually display comet-like characteristics, finding a ring around them is odd. Nonetheless, in 2013, astronomers discovered two rings around Chariklo, making it the first minor planet to have rings. This centaur has a diameter of approximately 250 kilometers.

Chariklo, observed by Webb

To find out more about this minor planet, scientists used the state-of-the-art space telescope James Webb to spy on Chariklo. Observations demonstrated its ability to explore objects in the Solar System, specifically the rings of the remote planetoid Chariklo. On October 18, 2022, Chariklo happened to pass in front of a star, and it was a perfect moment for Webb to turn its cameras and see what it could find. As Chariklo passed in front of the star, it blocked out some of the light./ This is a process known as occultation. To the surprise of astronomers, the star blinked twice before it disappeared and then blinked another two times after it emerged. This odd light curve was caused by the two rings of Chariklo.

Using NIRCam

To make the observation, scientists used Webb’s NIRCam instrument and turned it towards a star called Gaia DR3 6873519665992128512. It was in front of this star that the minor planet passed, allowing scientists to make observations. NIRCam has two major tasks; it is used as an image from 0.6 to 5 microns in wavelength and as a wavefront sensor that helps all of Webb’s 18-section mirrors function as one. Here is a video composed of 64 individual observations with Webb’s Near-Infrared Camera Instrument.

Observations of Chariklo by the James Webb Space Telescope. Image Credit:  NASA, ESA, CSA, Nicolás Morales (IAA/CSIC).
Observations of Chariklo by the James Webb Space Telescope. Image Credit: NASA, ESA, CSA, Nicolás Morales (IAA/CSIC).

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Written by Ivan Petricevic

I've been writing passionately about ancient civilizations, history, alien life, and various other subjects for more than eight years. You may have seen me appear on Discovery Channel's What On Earth series, History Channel's Ancient Aliens, and Gaia's Ancient Civilizations among others.

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