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This diffuse core extends to about 60% of Saturn’s radius — a huge jump from 10 to 20% of the planet’s radius that a traditional core would have.

One of the most daring aspects of the study is that the results were not obtained from direct core measurements – which we could never have done. Instead, Mankovich and Fuller turned to seismographic data on Saturn’s rings first collected by NASA’s Cassini mission, which explored the Saturn system from 2004 to 2017.

“Saturn, in fact, always rings like a bell,” says Mankovich. When the core vibrates, it creates gravitational perturbations that affect the surrounding rings, creating subtle “waves” that can be measured. As the planet’s core wobbled, Cassini was able to study Saturn’s C ring (the second block of rings from the planet) and measure the small but constant gravitational “ring” caused by the core.

Mankovich and Fuller studied the data and created a model of Saturn’s structure that would explain these seismographic waves – and the result was a fuzzy interior. “To date, this study is the only direct evidence of a diffuse core structure in a liquid planet,” says Mankovich.

Mankovich and Fuller believe that this structure works because rocks and ice near the center of Saturn are soluble in hydrogen, which allows the core to behave like a liquid rather than a solid. Their model suggests that Saturn’s diffuse core contains rocks and ice that add up to more than 17 times the mass of the entire Earth, so there’s a lot of material waving around.

The scattered core can go a long way in how Saturn works. Most importantly, it stabilizes some of the interior space from convective heat that would otherwise stir up Saturn’s interior with turbulence. In fact, this stabilizing influence generates internal gravitational waves that affect Saturn’s rings. Moreover, a diffuse core could explain why Saturn’s surface temperatures are higher than conventional convective models suggest.

However, Mankovich acknowledges that the model has some important limitations. He cannot explain what scientists have observed about Saturn’s magnetic field, which is strange in many ways (for example, it exhibits near-perfect symmetry about its axis, which is rather unusual). He and Fuller hope that future research will be able to narrowly restrict the interior and give scientists an idea of ​​how the planet’s core might affect its magnetic field.

They also hope NASA’s Juno mission can reveal a similar diffuse core within Jupiter. This will go a long way in confirming the suspicion that when giant planets are formed, this process naturally creates gradients of material, rather than pure and solid cores. Several studies using Juno’s gravity data also support this idea.