Saturn’s Rings Are Like a Seismometer Revealing the Planet’s Core

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Saturn’s icy rings are not just aesthetically wonderful wonders. One of them also records beautiful planetary music.

Hidden under a blanket of mostly hydrogen gas, the interior of the planet is shaking. This causes shifts in the local gravitational field that attracts particles in Saturn’s wide C ring and makes them dance. These distinctive jumps can take the form of spiral waves, and different wave clusters reveal features of certain features of Saturn’s interiors.

In other words, Saturn is an orchestra. Different notes appear on the C ring, just like those on the notes. Scientists can read these notes, hear the music, and identify the individual instruments and musicians playing it – all without seeing the orchestra itself.

using incoming data Cassini mission ending in 2017Over the years, scientists have listened to and deconstructed various symphonies on Saturn’s C ring. Now, two researchers from the California Institute of Technology — Christopher Mankovica planetary scientist and Jim Fuller, a theoretical astrophysicist – has decoded enough of this music to hear the sound of one of Saturn’s most amazing features: its nucleus.

According to their article published Monday in the journal Nature Astronomy, the core is huge: It makes up 60 percent of the planet’s radius and is 55 times the mass of the Earth. And unlike the ordered pile of solid metallic, rocky or icy matter found on other worlds, Saturn’s core is a monstrous mix of various rocks and ices mixed with a liquid. metallic form of hydrogen. The findings bring researchers closer to understanding how other gas giants like it were born, including Saturn and Jupiter.

“It’s a beautiful story,” he said. Linda Announcer, the project scientist for the Cassini mission at NASA’s Jet Propulsion Laboratory, who was not involved in the study.

Earth, moon and (most recently) geological viscera Anthem It was mapped with seismometers, instruments that record the journeys of seismic waves that move around the planet and behave differently as they mechanically pass through different layers. Lacking a solid surface, Saturn makes this type of detective work impossible.

By detecting subtle changes in gravity, the orbiting spacecraft can roughly map the inner layer cake structure of a gaseous planet. But Saturn’s core has such a weak influence on the planet’s gravitational field that this trick cannot be used to visualize it fully.

Fortunately, the glow of Saturn’s C ring revealed that conventional techniques could not. On last thirty yearsscientists have been to observe The ring’s strange spiral waves are in images from both Voyager missions and Cassini. And they after all logical that these spirals are caused by huge oscillations inside Saturn.

Dr. “They’re just constant earthquakes that exist all over the planet,” Mankovich said.

It is a technique known as “chronoseismology”: “kronos” is the Greek word for Saturn, and “seismo” relates to tremors. Used to solve another puzzle in 2019: How long is a day on Saturn? (About 10 and a half Earth hours.)

Now Saturn’s core is illuminated. Earlier models portrayed the planet as a distinctively layered cosmic jaw-breaking candy. Chronoseismology has revealed the complex truth. The core consists not only of rock and ice, but also of liquid metallic hydrogen, which was previously assumed to be a separate layer. It has more rock and ice at its center and more fluid metallic hydrogen at its outer edges – but everything mixes up in a chaotic cocktail from start to finish. Along with the transition from fluid to gaseous hydrogen, this article portrays Saturn as one big fuzzy ball.

Despite the continued success of the technique, scientists still don’t know what causes the nucleus to oscillate and create these spiral waves in the C ring. It resonates like a bell when the Earth is shaken by strong tectonic tremors. “But Saturn is fluid, so where are the earthquakes?” asked Mark Marley, a planetary scientist at the University of Arizona and an early chronoseismology pioneer who was not involved in the study.

The orchestra’s musicians may finally be known, but the hunt for the elusive conductor continues.

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