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Discovering the internal structure of giant gas planets, like Saturn, is very difficult. However, the ripples of its rings could reveal the nature of this giant planet’s core.
Saturn is the second largest planet in the solar system, a gaseous planet made up of a large proportion of hydrogen gas and a smaller proportion of helium. However, our knowledge of its internal structure is limited to computer simulations, which are difficult to verify due to the difficulty of obtaining practical data revealing the core of the giant planet.
Observation of the interior of the planets
Studies of the interior of planets depend on tracking waves generated by earthquakes, as in the case of studying the interior of the Earth. Studies of the interior of the sun also depend on observing the oscillations of the solar photosphere, or what is called the photosphere. However, observing similar waves in the case of gas planets such as Saturn and Jupiter is very difficult.
Moreover, the first information available on the distribution of the internal mass of Saturn comes from the measurement of the variation of the gravitational field around the planet.
This is done by accurately measuring the movement of satellites orbiting the planet. However, the number of spacecraft that have visited Jupiter and Saturn is too small to measure the gravitational variation around them. So knowing the internal structure of Saturn, for example, was difficult.
However, a recent study – published in the journal Nature Astronomy on August 16 – indicated that the oscillations within Saturn’s interior make the giant planet tremble very slightly. What causes ripples in the rings of Saturn, these small particles which revolve around the orbit of the planet.
This is what Saturn’s core, which is 55 times the mass of Earth (Kaltech), might look like.Astonishing results
So, scientists at the California Institute of Technology studied these undulating rings to reveal any new information about Saturn’s internal structure. Scientists relied on ancient data collected by the Cassini-Huygens probe during its 13-year orbit around Saturn.
According to the press release – released by the Caltech Institute – the study results indicated that Saturn’s nucleus is not a solid rock ball as some previous theories suggest, but rather a soup of ice, of rocks and mineral fluids. The study also showed that the planet’s core spans about 60% of its diameter, making it much larger than expected.
The results indicate that the mass of Saturn’s core is 55 times that of Earth. Ice and rock make up 17 land masses, with the rest of the mass coming from hydrogen and helium.
And Jim Fuller, associate professor of astrophysics at Caltech and co-author of the study, says they used “Saturn’s rings as a giant seismometer to measure oscillations inside the planet.”
“This is the first time that we have been able to verify the structure of a giant gas planet. The results are amazing,” he says.
On a related note, Jennifer Jackson, a physics professor at Caltech, who is not involved in the study, points out that “a thorough analysis of Saturn’s undulating rings is an elegant form of seismology that aims to understand the properties of the nucleus of Saturn “.
mixed soup
So far, these results provide the best evidence for the internal structure of Saturn’s core, which is consistent with recent evidence made available by NASA’s Juno mission, which indicates that the gas giant Jupiter may contain a similar core. .
About this nucleus, Christopher Mankovitch, the study’s principal investigator, comments that it is “like mud. It mixes hydrogen and helium as it moves towards the center of the planet. with more and more ice and rocks “.
Mankovic adds that “Saturn is in a constant state of vibration, but it is light. Its surface moves about a meter every hour to two hours, like a slowly rippling lake. Therefore, Saturn’s rings detect disturbances. gravitational and start to vibrate after them, similar to what happens in a seismograph. ” .
The observed gravitational disturbance model indicates “the stability of the inner part of the planet’s core. This can only be achieved if the proportion of ice and rock gradually increases as we approach the center of the planet,” explains Fuller.
“This means that the center of the planet contains stable layers that formed after the heavier materials settled in the middle of the planet and stopped mixing with the lighter materials above,” Fuller concludes. .
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