Here's how:
* Seismic waves travel differently through different materials. There are two main types of seismic waves:
* P-waves (primary waves): These are compressional waves that can travel through solids and liquids.
* S-waves (secondary waves): These are shear waves that can only travel through solids.
* S-waves cannot pass through the outer core. When scientists analyze seismic waves from earthquakes, they notice that S-waves disappear when they reach the outer core and reappear on the other side. This indicates that the outer core cannot support shear waves, which means it must be liquid.
This is just one piece of the puzzle, but it's a powerful one! Scientists have further confirmed this through other evidence, like Earth's magnetic field.
