Another Ringed Planet? Chiron May Possess Saturn-Like Rings


Chiron is a minor planet on the outskirts of the solar system first discovered in 1977. Astronomers observing the body as it passed in front of a star in November 2011 found evidence that this distant body may posses a ring system.

Light from the star was blocked for a short period in a manner consistent with a ring network. However, it is also possible that the observations were the result of streams of material emanating from the body, or a spherical cloud of gas and dust surrounding Chiron.  Several planets in our solar system, most notably Saturn, are accompanied by networks of rings. These include Jupiter, Uranus and Neptune.

Centaur objects exhibit some qualities of asteroids, while being similar to planets in other aspects. Another one of these objects, Chariklo, was previously identified as being accompanied by a ring system. This discovery came as a surprise to astronomers who had previously believed that Centaurs are slow to change.

"It's interesting, because Chiron is a centaur -- part of that middle section of the solar system, between Jupiter and Pluto, where we originally weren't thinking things would be active, but it's turning out things are quite active," Amanda Bosh from the Department of Earth, Atmospheric and Planetary Sciences at the Massachusetts Institute of Technology (MIT) said.

Chiron has shown some activity in the past, including occasional brightening of its surface, seen in observations taken in the late 1980's. This body appears to be acting, in many ways, like a comet, sending jets of gas and dust into space.  

When Chiron passed in front of a star on November 29, 2011, astronomers viewed the event from a pair of observatories in Hawaii, the Las Cumbres Observatory Global Telescope Network and the Infrared Telescope Facility. If Chiron were a solitary, dormant body, the star would have been blocked for a few seconds, then immediately would have been seen again. Instead, researchers found the light blinking in and out before and after the occultation. This effect could be explained by the presence of a ring system or a cloud of material surrounding the object.

Astronomers are uncertain how Centaurs could form such a ring system. One possibility is that the material orbiting Chiron may be left over from the formation of the body. Another idea is the debris may be left over from ancient collisions, and was later captured by Chiron.

Due to their nature of being similar to both planets and asteroids, Centaurs are named after the mythological creatures which were crosses between men and horses. Astronomers believe there may be 44,000 of these objects orbiting the Sun between Jupiter and Pluto.

If detection of a network of rings around Chiron is confirmed, the finding could suggest these features are more common around Centaur objects than previously believed.

Analysis of the potential ring system around Chiron was profiled in the journal Icarus

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