Compared to Saturn, Jupiter is only weakly equipped with rings. Its large moons are probably to blame.
Kane and Li's next focus is on Uranus and its rings. The two want to know how long the planet's rings might last. Some astronomers believe Uranus tipped on its side as a result of a collision with another celestial body. Its rings could be the remnants of that impact.
Spectrum of Science
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Jupiter should actually have powerful rings, even more magnificent than those of Saturn. But the big gas planet lacks them, a fact that astronomer Stephen Kane from the University of California in Riverside could not shake. Together with Zhexing Li, he has analysed the reasons for Jupiter's ringlessness. Their study, previously published on the arXiv, points to the planet's four large moons: they prevented rings from forming.
To do this, the two astronomers used a dynamic model in which they simulated the orbits of the four main moons and the planet itself. The modelling spanned periods of time that are necessary for rings to develop from dust. Saturn's rings, for example, consist mostly of ice, some of which comes from comets, which are also mostly frozen water. When moons are massive and large enough, their gravity can fling the ice out of a planet's orbit, or change the orbit of the material so that it eventually collides with the moons.
The Saturn has about 80 moons, slightly more than Jupiter. But the latter has four very large satellites, while Titan is the only heavyweight orbiting the ringed planet. "We found that Jupiter's Galilean moons, one of which is the largest moon in our solar system, would destroy any large rings very quickly. And that's before they form properly," Kane says. Therefore, he says, it is unlikely that Jupiter had large rings at any time in its past.
All four major planets in our solar system - Saturn, Neptune, Uranus as well as Jupiter - do indeed have rings. However, both Neptune's and Jupiter's rings are so thin that they are difficult to image with normal observing instruments. However, in some images from the newly commissioned James Webb Space Telescope, Jupiter's faint rings can be seen.
