Researchers have found a way to measure the spiral density waves of Saturn's rings. They have found that an optical illusion has misled astronomers about the real size of Saturn's most opaque ring.

When it comes to Saturn's rings, astronomers assumed that the brightest, densest sections (B ring) are the largest while the least transparent ones are the smallest. The research team came up with a mathematical formula to measure Saturn's spiral density waves from inside the ring, which were taken by NASA's Cassini mission.

They compared the data of the darker and lighter rings and discovered that the rings are roughly the same weight. It was a surprising discovery that researchers attributed to an optical illusion, although the cause of such illusion remains vague.

The study's lead author Matthew Hedman says it remains unclear how ring regions containing the same amount of material can vary in opacities. He speculated that it might be linked to the density or size of individual particles. The ring structure could also be in play.

"By 'weighing' the core of the B ring for the first time, this study makes a meaningful step in our quest to piece together the age and origin of Saturn's rings," said Cassini project scientist, Linda Spilker at Jet Propulsion Laboratory.

The rings' estimated ages were also derived from their perceived size. A less heavy ring would evolve much faster compared to a ring that contains more material. This suggests that the B-ring could be much younger than originally observed by at least a few hundred million years.

"Appearances can be deceiving," added study co-author Phil Nicholson who likened the deception to a meadow and a swimming pool. A misty meadow appears more opaque than a clear swimming pool. The latter is much denser and contains more water. The recent study was published in the journal Icarus on Feb. 3.

When the Cassini mission ventures into its final phase, it will collect more measurements for further studies. The spacecraft is set to pass through Saturn's rings in 2017. The additional data will help astronomers and scientist calculate the true age and mass of Saturn's most iconic features.

Photo: Alan Taylor | Flickr

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