Image: NASA
Saturn’s rings are such a spectacle that you can see them through even a modest telescope. Made mostly of water ice, the rings contain countless particles, large and small, that orbit the planet in a thin plane. For decades scientists have known that gravitational tugs from Saturn’s many moons imprint patterns on the rings. Now they have discovered a new ring sculptor: oscillations of the planet itself, which promise insight into the interior of the solar system’s second-largest planet.
The discovery came about because of a close inspection of Saturn’s rings. From outermost to innermost, the three main rings are named A, B and C. In 1980, when the Voyager 1 spacecraft flew past, it found grooves in each ring that resemble those on a vinyl record. The gravitational pulls of Saturn’s moons make waves, mostly in the A ring, because that’s the one closest to the moons.
In 1991, however, Paul Rosen, then at Stanford University, and his colleagues used Voyager data to discover waves in the C ring, the one nearest the planet. Although the moons accounted for some of these waves, no one knew what caused the others.
