Here's why:
* High Density: Saturn's density is surprisingly high for a gas giant, suggesting a dense, heavy core.
* Magnetic Field: Saturn's magnetic field is strong, hinting at a conducting core, possibly made of solid materials.
* Gravitational Measurements: Studying the planet's gravitational field suggests a concentrated mass at its center, consistent with a solid core.
However, it's important to note that:
* Not Directly Observed: We haven't sent a probe that can directly observe the core.
* Possible Composition: The exact composition of the core is still debated. It's likely a mix of rock, metal, and possibly even ice.
So, while we haven't directly confirmed it, the available evidence strongly suggests that Saturn has a solid core.