Astronomers use spacecraft to weigh one of Saturn's rings
A team of astronomershas succeeded in weighing the core of Saturn's brightest ring, knownas the B ring, for the first time. The discovery, which made use ofdata collected by NASA's Cassini spacecraft, may lead to numerousinsights regarding the age and formation of the ring system.
The ring's mass wasdiscovered using Cassini's visible and infrared mapping spectrometer,which observed fine-scale ring features known as spiral density wavesby analyzing the light from a number of bright, distantstars as it passed through Saturn's B ring.
The team noted thateven though the opacity of the ring varied greatly from region toregion, the mass of the ring was relatively unchanged leavingscientists uncertain as to what may be causing the disparate levelsof opacity and reflectiveness.
"Appearances canbe deceiving," states co-author of the study Phil Nicholson ofCornell University, Ithaca, New York. "A good analogy is how afoggy meadow is much more opaque than a swimming pool, even thoughthe pool is denser and contains a lot more water."
According to theresearchers, it is possible that the high levels of opacity inSaturn's B ring could result from a population of large particles, orpossibly an as-of-yet unknown aspect regarding the structure of thering.
The results of thestudy may inform the prevailing theories regarding the formation ofSaturn's iconic ring system, as well as its age. For example, whilstthe density of B ring's mass did not vary much from area to area, theoverall mass was markedly lower than had been predicted.
As a ring develops, itaccrues a significant amount of dust from meteorites and othersources,which acts to darken the ring and increase its mass.Therefore, since Saturn's B ring has a lower-than-expected mass, itis possible that it is much younger than had previously beenbelieved. The researchers estimate that the ring may only be a fewhundred million years of age rather than the few billion years thathad previously been theorized.
Whilst Cassini isentering the twilight of its career, the probe is far from done withuncovering the mysteries of the ringed giant. As part of its grandfinale, the probe is set to perform the most accurate measurement todate of the mass of the planet minus its ring system, allowingscientists a rare opportunity to gain an accurate reading of the massof Saturn's rings.
A paper on the findingshas been published online in the journal Icarus.