Exactly how could you tell what the interior of another planet is like?
If it’s a rocky planet such as Mars, we might send a probe on to the surface to measure seismometer, and after that create a model of the inside of the Martian spacecraft determined by the data gathered. How could we do that for a gasoline giant? There is not any surface to come down on, and even if it did, the pressure of the environment would crush any instruments long before they reached it.
Researchers have finally discovered a way to look inside Saturn’s rings, making use of them as a seismometer. The results, published in this week’s Nature Astronomy, could redraw the conventional model for how gas giants form.
Journey to the center of Saturn
The rings of Saturn are made up of several little items. These things orbit the earth and therefore are subjected to external forces such as gravity, which come from a number of directions. In case one thing unusual occurs, like oscillations within the body of the gasoline giant, the rings are able to “ripple” as shifts in the forces acting on them roll with the ring.
Saturn is not always a relatively calm ball of gas, but continuously moving. These little shifts, possibly one meter every hour or two, cause the gravitational field emanating out of the earth to take various shapes. This leads to ripples in the C-Ring, that could be noticed easier. These ripples have been seen for many years and the information from the Cassini mission was of special use.
By measuring these ripples, and dealing with their movements as lines on the output of a seismometer, the authors could figure out how the inside of the earth was oscillating, and what conditions should exist for the oscillations to occur. Making use of this data, a new and improved model was developed of the center of Saturn.
Even though the new findings are comparable to the old models which recommended a central core of ice and rock surrounded by a separate layer of metal hydrogen, they suggest that all the details are a bit more well-mixed than previously believed. This “fuzzy” core seems to be a lot bigger than previously thought, covering almost 60 percent of the planet’s diameter, the researchers said.
Christopher Mankovich, the chief author, described what this core is like:
“The fuzzy cores are like a sludge. The hydrogen and helium gas in the planet gradually mix with more and more ice and rock as you move toward the planet’s center. It’s a bit like parts of Earth’s oceans where the saltiness increases as you get to deeper and deeper levels, creating a stable configuration.”
The new design puts into question our present understanding of how gas giants form. While the standard model assumes a small, solid core that draws in gas, the “fuzzy” nature of Saturn’s core suggests that gas could be drawn into the formation process earlier than expected.
It’s still a mystery why a world without a solid core experiences oscillations. But we will keep watching.
