The Earth is akin to a rocky, molten-in-the-middle nesting doll – or perhaps a rotting, soft-centered onion, though the latter analogy affords our majestic planet much less dignity.

Although only several handfuls (39 fingers’ worth, to be exact) of people have alighted on the ocean’s deepest depths or upon the surface of the Moon, there’s one relatively nearby alien environment that no human will ever personally explore: the Earth’s core.

Approaching it, each Earthly layer differs in composition and increases in pressure and temperature, displaying unique material properties that become murkier the deeper we delve.