Saturn’s Seismic Activity Makes Waves in Its Iconic Rings

Scientists uncover new insight into the planet’s core based on observations of its rippling rings

Saturn Core
An illustration of Saturn and its "fuzzy" core. Caltech/R. Hurt (IPAC)

From studying Saturn’s rippling rings, scientists now have a new theory about the second-largest planet's core: it may be a little “fuzzy.” That is, the center of Saturn is not solid and has no clear definition—and it’s more massive than previously imagined.

Astrophysicists at the California Institute of Technology came to this conclusion after studying data gathered by NASA’s Cassini spacecraft, which orbited the ringed planet for 13 years. Their findings, published in the peer-reviewed journal Nature Astronomy, suggest that Saturn has a core made of ice, rock, hydrogen and helium-based fluids covering about 60 percent of the planet's diameter, reports Ashley Strickland of CNN.

“The fuzzy cores are like a sludge,” lead author Christopher Mankovich, a CalTech postdoctoral planetary scientist, tells CNN. “The hydrogen and helium gas in the planet gradually mix with more and more ice and rock as you move toward the planet’s center. It’s a bit like parts of Earth’s oceans where the saltiness increases as you get to deeper and deeper levels, creating a stable configuration.”

Mankovich and co-author Jim Fuller, a CalTech astrophysicist, realized the rippling rings might reveal new insight into the planet. After analyzing this wiggling, they built a model showing how Saturn’s center could cause the movement, reports Amir Malewar of Tech Explorist.

“We used Saturn’s rings like a giant seismograph to measure oscillations inside the planet,” Fuller says in a CalTech statement. “This is the first time we’ve been able to seismically probe the structure of a gas giant planet, and the results were pretty surprising.”

Once the researchers realized that ring oscillations were being caused by seismic activity within the planet, they were able to gain a better understanding of why that was occurring, CNN reports.

“Saturn is always quaking, but it’s subtle,” Mankovich says in a statement. “The planet’s surface moves about a meter every one to two hours like a slowly rippling lake. Like a seismograph, the rings pick up the gravity disturbances, and the ring particles start to wiggle around.”

In addition to being fuzzy, the planet’s core is huge. The astrophysicists estimate it is 50 times larger than Earth and not very well defined, meaning its edges are more diffuse than a traditional compact core. Rocks and ice at the center of Saturn gradually give way to the gas that makes up the rest of the planet, reports Isaac Schultz of Gizmodo.

The scientists speculate that this model of behavior may also be true of other gas giants, like Jupiter, the largest planet in the solar system. If the cores are fuzzy as the study indicates, it could change the way scientists view the development of planets.