Saturn’s Marriage Story
Before and after rings.
I’m universally proclaiming that we all like Saturn. A lot of us like Beyoncé too. Beyoncé told us to put a ring on the things we like. Accordingly, we see that Saturn has rings. However, if we went back in time to meet the dinosaurs, we might find that they didn’t share our admiration for the planet. Or Beyoncé.
RIP Cassini.
On September 15, 2017, NASA’s Cassini spacecraft fell to its doom after entering Saturn’s hostile atmosphere, concluding 13 years of studying the ringed planet. Yet even after more than a decade of service, it still had one last trick up its mechanical sleeves. For months before its end, Cassini performed its “Grand Finale”—an ambitious manoeuvre diving between the main body of Saturn and its rings a total of 22 times. During this period, Cassini gathered its last set of data, which upon interpretation had scientists a tad bit confused. Or y’know, 4.4 billion years confused.
See, we used to think Saturn always had its rings. We assumed they were as old as the Solar System itself, making them about 4.5 billion years old. However, data from Cassini suggests the rings are no more than about 100 million years old, even to a minimum value of just 10 million. For reference, dinosaurs still roamed the Earth 65 million years ago. Let’s see how scientists discovered the controversy of the rings’ age.
Dirty rings.
The claim that Saturn’s rings are dinosaurian artifacts was first proposed in a 2019 paper published in Science. The authors used data on the changing composition of the rings collected during Cassini’s Grand Finale to make assumptions on the matter accumulation rates within the rings.
Saturn’s rings don’t have a constant mass or composition. “Pollutants” within space—dust and other organic material coming from supernova explosions or interstellar collisions—accumulate in them. So while they’re mostly ice and water, about 1% of the rings have ended up being composed of pollutant material today.
Cassini measured the rates of pollutant accumulation in Saturn’s rings and determined that it would take between 10 to 100 million years for them to be as polluted as they were. The spacecraft collected months of data to support this claim. Months of data that ripped apart centuries of “understanding”. Obviously, compared to our previous assumption that Saturn’s rings are 4.5 billion years old, the range Cassini suggested is just a bit more than nothing. It’s almost as if the rings are the babies of a middle-aged Saturn.
But…
As Ned Stark once said, “nothing someone says before the word ‘but’ really counts”. And unfortunately, science tries really hard to be complicated. Even though the prospect of Saturn’s rings being younger than the dinosaurs is fascinating, there’s also a chance the whole theory is bogus.
There are certain uncertainties that challenge the new figure for the ring’s age. For example, it could be possible that Cassini’s measurements were taken during a period of unusually high pollutant bombardment. We also know that material from the rings rains down to Saturn’s main body. It keeps the composition of the ring changing, though we never actually figured out what the percent composition of that rain was. Until Cassini. Surprisingly, only about 24% of the ring’s rain was ice and water. For reference, the rings are made of 95–99% ice and water. This indicates that by some process, pollutant material—exactly what was used to make the assumption that the rings are just between 10–100 million years old—was preferentially being rained down to Saturn. Well, that’s the best explanation we’ve been able to come up with, at least. And if these two factors are consistently true, we might again have mispredicted the age of Saturn’s rings, though this time undershooting the correct value.
Still, the 10–100 million years theory remains the leading answer for Saturn’s rings’ age. The next step towards improving the accuracy of this figure would only be helped by answering the following question:
How were the rings formed?
And that's the problem. We have no clue.
We have theories. Saturn’s rings might be a culmination of the remnants of interstellar bodies that were torn up by Saturn’s gravity and products of collisions. But we’re not quite sure, sure.
Planetary scientists have been working on trying to answer this question for a while now. And I’d love to try and contribute something to this pending discovery, but if the people at NASA can’t quite figure it out, I’m not sure how far my binoculars can take me.
The divorce.
Though I might not be able to come up with an answer to how Saturn’s rings were formed, I can certainly still admire the rings. And I’d recommend you to do the same, while it's still possible.
As we know, the rings are made of mostly ice and water. We now also understand that some of that material will rain back down to Saturn. And I’m sure we can all imagine what would happen to ice if you put some in a microwave. Saturn’s gravity paired with radiation from the sun is slowly decaying the rings, and they’re expected to be completely gone in about 100 million years. They don’t seem much like babies anymore, do they?
The rings have come and will go. Saturn will still be here. The rings were never a certainty—never a definite feature of Saturn. Rather, they’re an accessory that happens to be in planetary fashion right now.
And as someone that always points out pretty skies and full moons, I’m just glad humanity coexists with the Saturn that’s still married.
