The TRUTH about the rings of Saturn!
You probably clicked on this article thinking, "Good heavens, what has happened to Saturn and what's this truth I so desperately need to know!?" Well, hush now, the truth is… it was clickbait all along, but now that you're here, you may as well stay for the duration, right? I mean, what kind of person can't sacrifice a few minutes to learn about space rocks? Let's get to it then on a geological journey of astronomic proportion that spans at least a couple of years.
Six planets and 1.4 billion kilometres away from the Sun, Saturn is the quintessential planet people imagine when picturing space. Named after the Roman God of agriculture, this big, bold and beautiful world captures people's imagination more than any other body in our solar system. The ring that gives Saturn its beauty has also captured our intrigue. Saturn is the second-largest planet in our solar system (behind Jupiter), composed predominately of hydrogen and helium. Despite 700 earths fitting within Saturn volume, it only has 95% of Earths mass due to its low density.
While Saturn is visible to the naked eye as a bright yellow star, it wasn't until 1610, when Galileo observed the planet with one of the earliest telescopes, that its primary characteristic revealed itself. However, he believed it to be a pair of moons on either side of the planet and further documented the "moons" disappearing two years later in 1612. Galileo witnessed a ring plane crossing, a cycle that occurs every 15 years where the edge of its rings faces towards the Earth, making them invisible in weaker telescopes. Dutch astronomer Christiaan Huygens was the first to document the rings for what they were, though the telescope Huygens used was far more powerful to Galileos credit. It would then be astronomer Giovani Cassini who would be the first to document the intricate ring structure and is the namesake for the Cassini spacecraft, which took scientific recordings of the planet from 1997 to 2017.
The rings themselves have been divided into an alphabetised naming scheme with astronomers in their infinite wisdom labelling them accordingly; E, G, F, A, B, C, D — With E being the furthest ring from the planet, D being the closest. This is because rings D, E, F and G are far fainter and were discovered more recently. The rings also decrease in orbital speed as they get further away from the planet (Similarly to the speed of planetary orbits around the sun). Compared to our satellite, the rings of Saturn travel much faster. The moon moves at around 1 km/s, D ring travels at 23.2 km/s (83 520 kph or 51 897 mph), and F ring travels at 16.4 km/s (59 040 kph or 36 686 mph) which technically is a legal speed on parts of the German motorway though I don't recommend travelling at such speeds.
The rings themselves are believed to be the product of many sources such as moons, comets and asteroids torn apart by the giants gravity. A vast proportion of the material is ice, and despite the ring system being over 100 000 km across, it's only ~1 km in width. Though peaceful looking, the rings themselves are a violent place, with each ring made up of many ringlets, with each ringlet made up of billions of pieces ranging from predominately dust-sized crystals to mountainous icebergs. This violence is what provides the rings with their surprising brightness for a system that is believed to be hundreds of millions, if not billions of years old. As the particles smash together, their surfaces are renewed, preventing dust from building up keeping the rings bright.
Much of the rings intricate make-up is the result of the complex gravitational tug-of-war and geological process of the moons of Saturn. Most impressive of which is the production of the outer E-ring. Unlike the inner rings, E-ring is exclusively composed of microscopic material and is more like a cloud than a flat disc. It is one of the faintest and widest at 2000km thick. Though personally, it's not its composition that's exciting but its origin and maintenance.
On Enceladus, geysers undergo constant cryovolcanic eruption, launching material at 800mph hundreds of kilometres into space. As the liquid freezes, it transforms into the icy cloud of E-ring and rains down onto nearby (astronomically speaking) moons coating them in a frosty white sheen.
Perhaps the most evident characteristic of how Saturn and its satellites influence the rings is the presence of the Cassini division and, on a smaller scale, the Encke division. The Cassini gap (Between B and A ring) and Encke gap (Within A ring) are caused by the moons Mimas and Pan, respectively, but gravitational interactions cause both. For the Cassini gap, as B-ring material is at its closest approach to Mimas (Located out past F-ring), they get caught in the moon's gravity; due to B-ring being able to orbit Saturn at twice the rate as Mimas, Mimas is always in the same position every other ring orbit. This regular gravitational interaction (known as orbital resonance) disrupts the trajectories of the particles in the B-ring. Any object within the Cassini gap will be jerked away from Saturn towards the moon, resulting in the gap.
The Encke gap operates similarly; however, rather than the moon being located outside the ring system, Pan is situated within the Encke gap. Gravitational interactions with the moon keep the gap devoid of most matter except for several diffuse ringlets found as companions for Pan within the gap.
The outer F-ring is also influenced by its gravitational interactions with the moons Prometheus and Pandora as they cause the ring to the coil and twist into a spiral. The list of how interactions with other astronomical bodies affect Saturn rings are numerous and complex, but those listed are the easiest to present.
For Astronomers, Saturns rings represent more than just a curiosity with a pretty view. The rings represent a local proxy to understand the processes and structure for how the early solar system would've looked during its formation 4.5 billion years ago, presenting us a window into our origin. I hope this article has provided you with a broader perspective on their majesty and processes.
If you want to know more, please follow the embedded links to the NASA gallery, which will allow you to explore more photos and descriptions. If I have made errors, grammatically or factually, please let me know on Twitter the link for which can be found on my homepage. If you liked this, I have a small catalogue of articles for you to explore at your leisure.
Have a good day & thanks for reading!
Affiliate link to Wonders of the Solar System by Brian Cox & Andrew Cohen, which was invaluable for this article: https://amzn.to/3xUKKtZ
