n A spherical body; a globe; especially, one of the celestial spheres; a sun, planet, or star
n One of the azure transparent spheres conceived by the ancients to be inclosed one within another, and to carry the heavenly bodies in their revolutions
n A circle; especially, a circle, or nearly circular orbit, described by the revolution of a heavenly body; an orbit
n (rare) A period of time marked off by the revolution of a heavenly body. --w:John Milton | John Milton