I use seismic waves to investigate the deep Earth and there are two main kinds: P Waves and S Waves. To explain their differences watch another snippet of the "Deep Earth Explorers" song (thanks again to @SedgwickMuseum, @DeepEarthExplor and @wearegeologise) #ScienceAtHome

The Earth's iron core is split into two parts, the liquid outer core and the solid inner core. The outer core was discovered because P Waves could travel through liquids, whereas the S Waves couldn't. To explain why, I've enlisted the help of my housemates... #ScienceAtHome

Unfortunately, after making various videos explaining P and S waves with my (extremely patient) housemates, they don't seem to want to upload!Oh well, I'll try again another day on my own personal account: @MatthewGeoKemp

Oo it worked! In the following gifs, my housemates ( @dj_colby, @BennethClarke and Ian Cawood) are the iron atoms in the core. In this first one, they are joined together in as a solid (like the inner core). P Waves, that vibrate forward and back, can travel through #ScienceAtHome

In the next gif, we're still in the solid inner core. S waves, that vibrate side-to-side, can also travel through it. #ScienceAtHome

Now we're in the liquid outer core, represented by the "iron" atoms being a bit further apart, and in this analogy not touching. P Waves can still travel through this liquid. #ScienceAtHome

But the S waves can't travel through the liquid due to the weaker bonds. Early seismologists could see that P waves travelled through the core, but S waves didn't, so they thought that the whole core was a liquid... (thanks to my housemates for doing this!) #ScienceAtHome

In 1936, Danish seismologist Inge Lehmann discovered that some S waves could travel through the inner core, suggesting that it was solid! Read about her and many other Deep Earth Explorations here: https://deepearth.esc.cam.ac.uk/  @DeepEarthExplor #ScienceAtHome