Uranus' rings are notoriously hard to spot. We didn't even know they existed until 1977, and since then the official ring count has climbed to 13.
The new data confirms that Uranus' brightest ring, called the epsilon ring, is different from other known planetary rings. It's doesn't have the usual accumulations of smaller, dust-size particles and is instead made up of rocks the size of golf balls and larger.
"Something has been sweeping the smaller stuff out, or it's all glomming together. We just don't know," said Edward Molter, a graduate student at the University of California, Berkeley, and co-author of a paper on the rings published in The Astronomical Journal. "This is a step toward understanding their composition and whether all of the rings came from the same source material, or are different for each ring."
There are several theories about how Uranus got its narrow, elusive rings. They could be busted-up pieces of moons, broken asteroids or even material left over from the planet's birth billions of years ago.
With the new temperature measurement, at least one lingering Uranus ring question has now been answered.
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