Article for Science

Solar nebula models have revolutionized conceptions of solar system formation
Solar nebula models have revolutionized conceptions of solar system formation

Jeff Cuzzi (SST) led a team of 23 members of the Cassini Rings Discipline Working Group, from six instrument teams, in writing an invited review article for Science, discussing Saturn’s Rings after more than five years of Cassini observations. The review article, which includes extensive online supporting material and several movies of dynamical models, has just been accepted and will be published in March. Amongst the main new insights are: (1) new moons have been found to clear several empty gaps, but other empty gaps are found to be devoid of moons; (2) ring structure is highly time variable – arcs and clumps appear and dissipate, and ring edges change their shape in a complicated way; (3) a new class of sub-km objects was discovered lying in three discrete bands in the outer, or A ring; (4) on the smallest scales (tens of meters) the rings break into a two-phase system of dense local gravitational instabilities separated by nearly empty gaps; and (5) the ring composition, while primarily water ice, contains either small organic molecules or actual “rust”, perhaps related to their newly discovered oxygen atmosphere. The age of the rings continues to be a major open issue.