Overview

Of all the planets that populate our Solar System, perhaps the most fascinating and majestic is Saturn: a gaseous colossus with an elegant ring system that dances around the Sun with its dozens of shepherd moons, completing a revolution every thirty Earth years. The distinctive cosmic jewel that delicately envelops it is made of trillions of tons of gas, ice, dust, and rocks and, according to experts, is about to disappear.

The science and other stuff to know

In 1979, NASA’s Pioneer 11 spacecraft became the first human-made device to fly past Saturn. A year later, Voyager 1 passed through the giant’s orbit and managed to photograph it. The first images from more than four decades ago of a cold, inhospitable, and distant world revealed endless mysteries about its nature: atmospheric variations, the density of the rings, and transverse spots that surround the giant on its equator. These phenomena seemed to be independent of each other until 1986, when a team of NASA scientists determined that the planet’s magnetic field dragged particles and water to the equator and higher latitudes, condensing clouds in the form of dark bands.

This same magnetic phenomenon ionizes the inner layers of the rings, denser and more continuous than the outer ones, — as J. E. P. Connerney suggests in his article— since it is formed mainly by dust and ice, which when ionized are attracted to the atmosphere of Saturn and fall toward it. The amount of material lost from the Gas Giant’s rings every half hour is equivalent to an Olympic swimming pool full of dust, says James O’Donoghue, lead author of a study recently published in Science. At this rate, the rings are expected to disappear in less than 100 million years: a cosmic blink compared to the four billion-year age of the colossus.

So what?

The concentric layers of Saturn’s rings distribute the finer, lighter material in the inner sub-rings and the larger rocks and bodies in the outer ones. The material in the rings moves with such a radial velocity that it stays in orbit around the planet, instead of hurtling toward it. The team determined that the presence of water ice in the inner rings is related to the discharge of water that takes place in the hazers of Enceladus, one of Satun’s moons.

These data are used to model the formation of rings, which could have occurred from a collision between moons and then been fueled by contributions from Enceladus and the gravitational attraction of dust and interplanetary material. Finding an accurate model will allow planetary astronomers to reproduce the former life of the rings of Jupiter, Uranus, or Neptune and perhaps discover that they were once elegant and precious systems, and now we only see their carcasses.

What’s next?

The team of experts led by O’Donoghue wants to continue studying Saturn and its lavish rings for a longer period since its seasons last approximately 7.5 Earth years, and the inclination of the rings with respect to the Sun varies markedly in each one. They anticipate significant changes in the intensity of material flow from Saturn’s rings to its atmosphere, because the rate of ionization and material yield is proportional to solar radiation exposure.