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Saturn boasts a highly distinct and characteristic ring (Image: Getty).
Saturn’s celestial rings are not merely ornamental adornments for the planet; they serve as a valuable tool for scientists to gain insights into the intricate workings of the planet’s core. A study was recently published on August 16 in the journal Nature.
Utilizing Saturn’s expansive ring system as a seismic instrument, researchers have investigated the processes occurring within the planet and identified that its core remains remarkably nebulous.
In contrast to the solid spherical core of Earth, Saturn’s core appears to resemble a mixture of rock, ice, and molten metal, creating a soupy consistency that significantly influences the planet’s gravitational forces.
This new study relied on data from NASA’s Cassini mission, which orbited Saturn and its moons for 13 years, spanning from 2004 to 2017.
In 2013, NASA’s mission data initially revealed that Saturn’s innermost ring, known as ring D, exhibited wave-like and swirling behavior that couldn’t be fully explained by the gravitational interactions of the planet’s moons.
This recent exploration of Saturn delved deeper into these movements within the planet’s rings to gain a more profound understanding of its internal processes.
Jim Fuller, an assistant professor of theoretical astrophysics at Caltech and co-author of the study, expressed, “This is the first time we’ve been able to probe the seismic structure of a massive gaseous planet, and the results are surprising.”
Saturn’s core is not only dense but also stretches over about 60% of the planet’s diameter, a substantial size much greater than previously estimated. Analysis suggests that Saturn’s core could be as heavy as 55 times the mass of the entire planet.
Christopher Mankovich, the study’s lead author and a postdoctoral scholar in planetary science within Jim Fuller’s team, explained that the core’s movements generate persistent surface undulations on Saturn. These surface waves lead to subtle variations in the planet’s gravitational field, consequently affecting the behavior of Saturn’s ring system.
“Saturn is in a constant state of vibration, though the resonance is very low. Every 1 to 2 hours, the planet’s surface moves by about 1 meter, akin to the slow ripples of a tranquil lake. Similar to a seismometer, the rings capture the gravitational fluctuations, and the particles within the rings begin to sway,” he described.
Mankovich likened the material within Saturn’s core to a dense slurry. Despite its stratified nature, the core’s fluid characteristics resemble the increasing salinity with depth observed in Earth’s oceans.
“Hydrogen and helium gases within the planet gradually mingle with progressively more ice and rock as they move towards the planet’s core,” he added.
This recent study of Saturn’s core has the potential to challenge existing models regarding the formation of gas giants – planets devoid of a solid surface, primarily composed of hydrogen and helium. These models traditionally assume that the rocky core of such planets forms first, followed by the accumulation of massive gas layers. However, if the cores of these planets are as fluid as Saturn’s, the gas amalgamation could take place earlier.
Recently, NASA’s Juno mission also shed light on why Jupiter, another gas giant in the Solar System, might possess a similarly ambiguous core structure akin to Saturn’s.