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Why doesn’t Jupiter have big, beautiful rings like Saturn does?

When you think of the iconic features of the planets in our solar system, one particular image that jumps to mind is Saturn with its stunning rings. But Saturn’s bigger next door neighbor Jupiter also has rings, although they are invisible in most images. The reason for this is rather complex, as a larger gas giant like Jupiter might be expected to have bigger rings than Saturn — but now researchers have figured out why this is.

“It’s long bothered me why Jupiter doesn’t have even more amazing rings that would put Saturn’s to shame,” said the lead researcher, Stephen Kane of University of California, Riverside, said in a statement. “If Jupiter did have them, they’d appear even brighter to us, because the planet is so much closer than Saturn.”

Artist rendering of Jupiter with rings that rival Saturn's.
Artist rendering of Jupiter with rings that rival Saturn’s. Stephen Kane/UCR

To understand Jupiter and the matter orbiting it better, Kane and colleague Zhexing Li modeled Jupiter’s four largest moons: Ganymede, Callisto, Io, and Europa.  They also looked at the planet itself and how much time it would take for rings to form around it, in work that will be published in the Planetary Science Journal.

It seems that the big moons are responsible for Jupiter’s ringless-ness. “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. “Massive planets form massive moons, which prevents them from having substantial rings.”

It is thought that Saturn and Jupiter’s rings may have evolved differently as well. While researchers originally thought that Saturn’s rings could have been a relatively recent addition of young ice particles, study with the Cassini probe showed that they are very old and likely formed in the early days of the solar system. Jupiter, however, got its rings later when small meteorites impacted the planet’s moons and threw up dust that formed into the rings. As for Uranus and Neptune, which also have faint rings, no one is quite sure how these formed.

Studying rings can help learn about how planets form, and how the solar system developed. Other researchers plan to use the James Webb Space Telescope to study the ice giants of Neptune and Uranus in more detail. “For us astronomers, they are the blood spatter on the walls of a crime scene,” Kane said. “When we look at the rings of giant planets, it’s evidence something catastrophic happened to put that material there.”

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