You've heard of the lithosphere by now, I'm sure. Likewise the biosphere and the atmosphere and maybe even the ecosphere. There are actually many different "-spheres" beyond those, enough to make a nested hierarchy extending from the whole solar system (the heliosphere) down to the Earth's inner core (the siderosphere). Is that useful, or just Victorian-style pseudo-objective nominalism? To help with this burning question, I've compiled a list of the various -spheres used in Earth science. See if you know them all.