Just how old are they?

What a wonderful mystery. Just how old are Saturn's rings? 100 million on the young side, 4.5 billion on the old. Take your pick as researchers are debating this age issue with delicious intensity.

To whit ...

As new perspectives often do, this one revealed a surprise. Previously, planetary scientists had assumed that Saturn’s rings were as old as the solar system itself — about 4.5 billion years old. But cosmic clues hidden deep within the rings caused some Cassini scientists to massively revise this figure. The rings aren’t as old as the solar system, they argued in a paper published this summer in the journal Science. They emerged no more than 100 million years ago, back when dinosaurs roamed Earth.

An explosion of media coverage linking the rings to the age of dinosaurs helped to quickly solidify the new findings in the public’s eye. If you enter the search phrase “how old are Saturn’s rings,” Google returns the answer “100.1 million years.”

Aurélien Crida, a planetary scientist at the Côte d’Azur Observatory, was incredulous at this definitive declaration. “I was a bit pissed off by how it was assessed, that the rings are young, and it’s over,” he said.

The mystery deepens ...

In response to the hypothesis, Crida co-authored a commentary for Nature Astronomy, published in September, that presented a litany of uncertainties. The dinosaurian age of the rings is an eye-catching claim, said Crida, but it circumvents an uncomfortable reality: Too many uncertainties exist to permit any firm estimate of the age of the rings. Despite Cassini’s heroics, “we’re not really far ahead of where we were almost 40 years ago,” back when the Voyager probes first took a good look at Saturn, said Luke Dones, a planetary scientist at the Southwest Research Institute in Boulder, Colorado.

Proponents of the younger age stand by their work. “Every new exciting result gets challenged,” said Burkhard Militzer, a planetary scientist at the University of California, Berkeley and a co-author of the Science paper. “It’s the natural way to proceed.”

The debate is about more than the narrow question of the rings’ age. The age of Saturn’s rings will influence how we understand many of Saturn’s moons, including the potentially life-supporting world Enceladus, with its frozen ocean. And it will also push us closer to answering the ultimate question about Saturn’s rings, one that humans have wondered about since Galileo first marveled at them over 400 years ago: Where did they come from in the first place?

Unlike religion, science is designed to be disproved. Awesome without question.