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Saturn’s rings aren’t just a beautiful adornment – scientists can use this feature to understand what’s going on deep down on the planet.
Using the famous rings as a seismograph, scientists studied the processes inside the planet and determined that its core must be “fuzzy”. Instead of a solid sphere like Earth’s, Saturn’s core appears to consist of a “soup” of rocks, ice, and metallic fluids that swirl around and affect the planet’s gravity.
The new study used data from NASA’s Cassini mission, which orbiting Saturn and its moons for 13 years between 2004 and 2017. In 2013, data from the mission first revealed that Saturn’s innermost ring, the D-ring, ripples and swirls in ways that cannot be fully explained by the gravitational influences of the planet’s moons. The new study looked at these movements in Saturn’s rings in more detail to better understand the processes inside.
The research is described in an article published Monday in the journal Nature.
“We used the rings of Saturn as a giant seismograph to measure oscillations inside the planet,” said Jim Fuller, assistant professor of theoretical astrophysics at Caltech and one of the authors of the article in a communicated. “This is the first time that we have been able to seismically probe the structure of a giant gas planet, and the results have been quite surprising.”
Not only does the core of the planet appear muddy, it also appears to extend over 60% of the planet’s diameter, making it much larger than expected.
The analysis showed that Saturn’s core could be about 55 times as massive as the entire planet Earth. Of the total mass of the nucleus, 17 land masses are made up of ice and rock, with the remainder being a fluid made from hydrogen and helium, the study suggests.
Lead author of the study, Christopher Mankovich, a postdoctoral fellow in planetary science who works in Fuller’s group, explained that movements in the nucleus constantly ripple Saturn’s surface. These surface waves create tiny changes in the planet’s gravity which then affect the rings.
“Saturn is still shaking, but it’s subtle,” Mankovich said in the statement. “The surface of the planet is moving about one meter [3 feet] every one to two hours like a slowly rippling lake. Like a seismograph, the rings pick up disturbances in gravity and the particles in the ring begin to wiggle.
According to scientists, the nature of these ring waves suggests that the core, despite its sloshing, is made up of stable layers of different densities. Heavier materials are found around the center of the planet and do not mix with lighter materials closer to the surface.
“For the planet’s gravitational field to oscillate with these particular frequencies, the interior must be stable, and this is only possible if the fraction of ice and rock gradually increases as you move towards the center of the planet. planet, ”Fuller said.
Mankovich compared the material of the core to mud, adding that the layered but liquid nature of the core is akin to the salinity of Earth’s oceans, which increases with depth.
“The planet’s hydrogen and helium gas gradually mix with more and more ice and rock as you move toward the center of the planet,” Mankovich said.
The findings could challenge some of the established patterns of formation of gas giants, planets without a hard surface, which are primarily composed of hydrogen and helium, the study suggests. These models assume that the rock cores of these planets first formed and then attracted large envelopes of gas. If the planets’ cores are fuzzy, however, as the study indicates, the planets could instead incorporate gas earlier in the process.
In fact, recent findings from NASA’s Juno mission suggest that another of the solar system’s gas giants, Jupiter, may also have a similar fuzzy core.
“Christophe [Mankovich] and Jim [Fuller] were able to show that a particular feature of the ring provided strong evidence that Saturn’s nucleus is extremely diffuse, ”said Matt Hedman, a planetary scientist at the University of Idaho, who was part of the team that first discovered that movements in Saturn’s rings can’t be fully explained by the gravity of its moons.
“I’m excited to think of what all of the other features of the rings generated by Saturn might tell us about this planet,” added Hedman, who did not collaborate on the new document.
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