Scientists using a spacecraft exploring Saturn "weighed" the large planet's most massive ring for the first time and discovered something unexpected.
A new analysis of data collected by the Cassini spacecraft found that even though the brightness and apparent opacity of parts of the ring varied, the actual amount of material within the ring -- known as the B ring -- remained pretty consistent throughout.
This kind of finding is counterintuitive, NASA said, because usually a more opaque substance "should contain more stuff" than something more translucent.
"Appearances can be deceiving," Phil Nicholson, co-author of a study about the discovery in the journal Icarus, said in a statement. "A good analogy is how a foggy meadow is much more opaque than a swimming pool, even though the pool is denser and contains a lot more water."
Researchers still aren't sure what could be causing the shift in brightness from one region to the next.
"At present it's far from clear how regions with the same amount of material can have such different opacities," Matthew Hedman, another co-author of the study said.
It's particularly surprising because the B ring can be up to 10 times more opaque than the A ring, Hedman added, and the total mass of the B ring is lower than initially thought.
"It could be something associated with the size or density of individual particles, or it could have something to do with the structure of the rings."
This study is in line with other research into Saturn's rings, NASA said, and it could help scientists learn more about the age of Saturn's most striking feature.
Scientists think that less massive rings likely formed more quickly than more massive rings. If the B ring is less massive than originally thought, it might be younger than expected. Instead of a few billion years old, the ring might be a few hundred million years old, NASA said.
While that might not sound like a huge difference, scientists examining the rings need to know the density of the rings in order to understand exactly how they formed.
"The rings are so magnificent and awe-inspiring, it's impossible for us to resist the mystery of how they came to be," Linda Spilker, Cassini project scientist, said in the statement.
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