If a material is thicker, it should be less transparent, right? It turns out that in Saturn's rings, that's not always the case. A new examination of the B ring shows that even though it's the most opaque of Saturn's rings, it's not the densest one.
ANALYSIS: Mysterious ‘Spokes' in Saturn's Rings are Still There
The puzzling result is not just isolated to this ring, either. Scientists have found similar results in other studies when looking at the gas giant's other rings, NASA said. This latest research comes from using the Cassini spacecraft, which is slowly wrapping up investigations at Saturn since arriving there in 2004.
"Appearances can be deceiving," said research co-author and Cassini co-investigator Phil Nicholson, at Cornell University in New York, in a NASA 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."
The research team looked at the ring's mass density by studying spiral density waves. These features appear when ring particles move under the influence of gravity - gravity from Saturn's moons as well as the huge gas giant planet itself. Each wave's structure depends on how dense it is, and the effect of gravity. Scientists now know that the B ring is less dense than it appears, but the full reason is still a mystery.
NEWS: Propellers Reveal Hidden Moons in Saturn's Rings
"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," stated Matthew Hedman, the study's lead author and a Cassini participating scientist at the University of Idaho.
While Saturn's rings are arguably the most spectacular in the solar system, it's not the only planet with rings. Jupiter, Uranus and Neptune also have faint ring systems of their own. Maybe this implies different origin stories, but more study will be needed to figure this out for sure. NASA says Saturn's rings - made up of billions of particles and pieces - are likely fragments of broken-up moons, comets or asteroids that were pulled apart under Saturn's gravity.