Earth about under the oceans to for the continents. The crust and the cold, rigid, top of the upper mantle are collectively known as the lithosphere, and it is of the lithosphere that the tectonic plates are composed. Beneath the lithosphere is the asthenosphere, a relatively low-viscosity layer on which the lithosphere rides. Important changes in crystal structure within the mantle occur at below the surface, spanning a transition zone that separates the upper and lower mantle. Beneath the mantle, an extremely low viscosity liquid outer core lies above a solid inner core. The Earth's inner core might rotate at a
Names for the human species "Gaian") is frequently used, as it were naming humanity by its planet of origin. Incidentally, this situation parallels the naming motive of ancient terms for humanity, including "human" ("homo", "humanus") itself, derived from a word for "earth" to contrast humans as earth-bound with celestial beings (i.e. deities) in mythology. Names for the human species The common name of the human species in English is historically "man" (from Germanic), often replaced by the Latinate "human" (since the 16th century). In addition to the generally accepted taxonomic name "Homo sapiens" (Latin: "sapient man", Linnaeus 1758), other Latin-based names for the human species