How do scientists know what lies inside the Earth?

[Campus reveiw]

We cannot directly observe most of Earth's interior, so scientists use indirect evidence to understand its structure.

One important source of evidence is seismic waves generated by earthquakes. These waves travel differently through different materials. Their speed and direction can change as they pass through boundaries inside Earth, helping scientists identify the crust, mantle, outer core, and inner core.



This raises some interesting questions for science learners:

Why do some seismic waves travel through solids but not liquids?

How does the liquid outer core differ from the solid inner core?

What can seismic wave patterns reveal about Earth's interior?

For a diagram and a clear introduction to the topic, see The Campus Review's guide:

https://thecampusreview.com/stem/layers-of-the-earth/

I'd be interested to hear which part of Earth's internal structure you find most fascinating.