Astronomers find changes in Saturn's rings

Astronomers have discovered that Saturn's D ring, the innermost of Saturn's 15 rings, has grown dimmer in the past 25 years and sections have moved up to 125 miles inward toward the planet. This discovery was made after astronomers compiled results predominantly from the Voyager 2 spacecraft, which passed Saturn in 1981, and the Cassini-Huygens probe which entered Saturn's orbit last year.

Other rings were found to be rotating slower than had previously been estimated with computer models. It was also discovered that the matter composing the rings is of far more widely varying temperatures than had been expected. Sections of Saturn's F ring were also recognised as breaking apart and reforming, depending on the location of one of Saturn's moons.

The rings, which are now iconic to Saturn, and known to be common to all Jovian planets in general, were first observed in 1610 by Galileo. The rings have recently become a subject of scientific interest to modern astronomers who believe they are similar in structure to the dust which orbited the Sun, in a similar pattern, and formed the planets some 4.5 billion years ago.

This, and other Cassini-related discoveries, were discussed at a meeting of the American Astronomical Society's division of planetary sciences on Monday.