Why don’t the rings of Jupiter look like those of Saturn?

These are exactly the questions that astronomers Stephen Kane and Zhexing Li of the University of California, Riverside pose in a recent paper now accepted for publication in the Journal of Planetary Science. After all, as the most massive planet in the solar system, they claim in the article, Jupiter’s history must be full of collisions, captures and other similar events that could provide abundant material for rings. more substantial.

To solve the mystery of Jupiter’s disappointing ring system, the duo turned to computer simulations to examine how the planetary system acts over periods of 1 to 10 million years. During this period, they examined the availability and orbital stability of icy material to form rings, essentially looking at the size and brightness of rings that could form, remain, or be destroyed. In particular, they looked at how Jupiter’s four largest satellites, the Galilean moons – Io, Europa, Callisto and Ganymede – affect the formation or longevity of water ice rings.

“We found that the Galilean moons of Jupiter, one of which is the largest moon in our solar system, would very quickly destroy any large rings that might form,” Kane said of the results of their simulations in a Press release. In part, that’s because massive moons can destabilize the orbit of icy particles to eject them from the system, or sweep the particles so they collide with the moon, rather than orbiting like a ring. Ultimately, Kane said, “Massive planets form massive moons, which precludes them from having substantial rings.”

It’s also consistent with reality – after all, Saturn’s rings are bright because they’re made up largely of ice, and probably still there (depending on their age) because researchers believe they’re continually being replenished by ice. many small icy moons embedded within them. . Jupiter’s dark, thin rings, on the other hand, are mostly dust likely from a few of its smaller moons.

So even if Jupiter had managed to build impressive rings of ice in the past, they wouldn’t have lasted long. And its current rings, small as they are, are probably quite young – less than 10 million years old. Saturn, on the other hand, appears to be in a “sweet spot” in terms of its ability to build and sustain a stunning large ring system over longer periods of time.

Extension to exoplanets

But Kane and Li’s research tells us even more, they say. Beyond the solar system, the pair also pondered what their findings could mean for exoplanets and their rings. After all, the rings are more than just superficial decoration – they also tell the story of a planet’s dynamic past, as well as that of its surroundings. While it’s difficult to form or maintain massive, easy-to-spot rings of ice, their discovery tells us something valuable about planets capable of hosting such spectacles. Ring systems could reveal information such as planetary age or details about the types of moons that should (or should not) be present, as well as the type or availability of materials such as icy comets or asteroids in planet solar system.

As astronomers continue to build our catalog of known exoplanets and point JWST to them for more, the details these worlds reveal — including their rings — will offer a wealth of valuable information about how stars and their planets form and evolve over time.

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