Saturn's mysterious rings, which have fascinated astronomers since Galileo's time, have radically changed over the past 25 years, according to unprecedented observations by the international Cassini spacecraft.
The planet's innermost ring - known as the D ring - has grown dimmer since the Voyager spacecraft flew by the planet in 1981. A piece of the D ring has also shifted 125 miles inwards, towards Saturn.
While scientists puzzle over what caused Saturn's D ring to change in such a short period, the observations could tell something about the age and lifetime of ringed planets.
Astronomers are also interested in Saturn and its rings because they are a model of the disc of gas and dust that initially surrounded the sun. Studying them could yield important clues about how the planets formed four-and-a-half billion years ago. The D ring finding was among several Cassini-related discoveries announced at a meeting of the American Astronomical Society's division of planetary sciences in Cambridge.
Scientists also found that ice particles which make up Saturn's main rings - the A, B, and C rings - were spinning much slower than expected.
Astronomers expected the denser A and B rings - where crowds of particles crash into one another like bumper cars - to rotate faster than the sparser C ring. The spin rates were determined by measuring the temperature of the particles.
Linda Spilker, a deputy project scientist working on the craft's results, said: "I don't think Saturn's rings will disappear anytime soon, but this tells us how the rings are evolving and how long they might last", "Scotsman" reported.