How do we know what the Earths interior structure when we can’t see it? We know by sending waves through the Earth. We also record the data from an earthquake. As the waves pass through we will be able to tell wher our planet is solid and liquid. Waves tell us alot about our planet.
We use S waves to tell us where there is a liquid. When there is a liquid the S wave will break apart. S waves cannot pass through liquids. P waves will also tell us where there are liquids. P waves slow down in a liquid. Scientists can use both to help figure out what the Earth’s interior looks like.