In astronomy, axis mundi is the Latin term for the axis of Earth between the celestial poles. In a geocentric coordinate system, this is the axis of rotation of the celestial sphere. Consequently, in ancient Greco-Roman astronomy, the axis mundi is the axis of rotation of the planetary spheres within the classical geocentric model of the cosmos. In 20th-century comparative mythology, the term axis mundi — also called the cosmic axis, world axis, world pillar, center of the world, or world tree — has been greatly extended to refer to any mythological concept representing "the connection between Heaven and Earth" or the "higher and lower realms." Mircea Eliade introduced the concept in the 1950s. Axis mundi closely relates to the mythological concept of the omphalos (navel) of the world or cosmos. Items adduced as examples of the axis mundi by comparative mythologists include plants (notably a tree but also other types of plants such as a vine or stalk), a mountain, a column of smoke or fire, or a product of human manufacture (such as a staff, a tower, a ladder, a staircase, a maypole, a cross, a steeple, a rope, a totem pole, a pillar, a spire). Its proximity to heaven may carry implications that are chiefly religious (pagoda, temple mount, minaret, church) or secular (obelisk, lighthouse, rocket, skyscraper). The image appears in religious and secular contexts. The axis mundi symbol may be found in cultures utilizing shamanic practices or animist belief systems, in major world religions, and in technologically advanced "urban centers." In Mircea Eliade's opinion: "Every Microcosm, every inhabited region, has a Centre; that is to say, a place that is sacred above all." Background There are multiple interpretations about the origin of the concept of the axis mundi. One psychological and sociological interpretation suggests that the symbol originates in a natural and universal psychological perception — i.e., that the particular spot that one occupies stands at "the center of the world." This space serves as a microcosm of order because it is known and settled. Outside the boundaries of the microcosm lie foreign realms that — because they are unfamiliar or not ordered — represent chaos, death, or night. From the center, one may still venture in any of the four cardinal directions, make discoveries, and establish new centers as new realms become known and settled. The name of China — meaning "Middle Nation" ( pinyin: