Saturn’s rings are one of the most recognized and revered celestial objects known to the human race. From a distance, they look like a disk of layered crystal or multicolored disks within disks that wrap around Saturn’s hazy umber face. When viewed up close, we see that these rings are actually particles of water ice (from microns to icebergs), as well as silicates, carbon dioxide, and ammonia.
We would also noticed that the rings have some interesting orbital mechanics. In fact, each ring has a different orbit that is the result of its proximity to Saturn (i.e., the closer they are, the faster they orbit). To illustrate what this complex system look like, NASA Fellow Dr. James O’Donoghue created a stunning animation that shows how each of Saturn’s major ring segments (A-Ring to F-Ring) orbit together around the planet.
Born in the UK, Dr. O’Donoghue is a planetary researcher and scientist currently working with the Japan Aerospace Exploration Agency (JAXA) who lives outside of Tokyo. Previously, he worked as a NASA Fellow at the NASA Goddard Space Flight Center where he specialized in the research of Saturn (and its ring system), Jupiter, and their atmospheric phenomena (aurorae, the Giant Red Spot, etc.)
Dr. O’Donoghue related what inspired this animation with Universe Today via email:
“Over the years I’ve received a lot of questions about what the rings are made of and how they move. People are often surprised that the rings are made of shards of frozen water ice ranging in size from dust to icebergs and that they orbit the planet at different speeds depending on what “lane” they’re in! By the way, the rings are made of almost pure water. If they were pure water ice though, they’d look white!“
As you can see from the animation, Saturn’s major rings are designated based on the order of their discovery and orbit their parent planet in the order of D, C, B, A, and F (innermost to outermost). Between the A- and F-Rings is the mysterious E-Ring, which orbits between Mimas and Titan and is extremely wide. This ring is composed of microscopic icy particles, which makes it hard to discern among the others.
The recording simulates what takes place around Saturn during the course of 30 hours. “The image of Saturn was made by images collected by the Cassini spacecraft which had been stitched together,” explained O’Donoghue. “Rendering can take a lot of time, so I thought the minimum useful animation would be to show the slowest ring lapping the planet twice.”
Saturn’s rings and moons have been the subject of scientific debate. A 2019 study showed that the migration of Saturn’s moons has widened the Cassini Division in Saturn’s rings. Credit: Cassini, Dante, Baillié and Noyelles
The orbital velocity and period of each ring is timed to illustrate the resonance the system of the rings. “The Cassini Division, the widest gap within Saturn’s rings, is caused by the resonance between a small moon called Mimas and ring particles,” said O’Donoghue. “Funnily enough, I was looking for some images on that and found something cool at UT.” (shown above).
Saturn’s own spin is indicated in white, which illustrates its rotational velocity relative to its ring system. Also visible is the persistent and rotating hexagonal vortex located around Saturn’s north pole. The animation not only presents a beautiful view of the orbital dynamics of Saturn’s rings. It also honors the Cassini mission, which ended its mission Sep. 15th, 2017, after thirteen years around Saturn.
The data collected by the probe is still being analyzed and leading to exciting new discoveries about Saturn, its rings, and its system of moons. Before plunging into Saturn’s atmosphere, Cassini conducted its “Grande Finale,” where the probe plunged into the unexplored region that lies between Saturn’s atmosphere and its rings.
The footage of Cassini’s final months, and its final descent into Saturn’s atmosphere, earned NASA an Emmy nomination.
Further Reading: YouTube