Using seismic data to probe mysteries
We know the Earth's core is not the jungle realm of Edgar Rice Burroughs or the bizarre rockspace of The Core (an indescribably terrible movie that manages, among other crimes, to waste Hilary Swank.) But what is it? Why and how does the core rotate faster than the rest of the planet? How is it losing heat to the surrounding rocks at 2-3 times the rate we thought it was (and that fits with current geological theory)? It's extremely weird down there to begin with. At 35 million atmospheres of pressure, terms like "liquid iron" lose their meaning: as geologist Bruce Buffet puts it, “If you could put on your safety gloves and stick your hands into the outer core, it would run through your fingers like water." The core houses currents and even, in a sense, weather, all occurring in this spinning, Mars-sized sphere.
In other words, there are major scientific mysteries about our own planet, as well as the distant ones.