The fundamental elements of an armillary sphere - like this one made in wood by Robert Marichy, a wood turner in Arinthod in the Jura department - are its armillas, which represent the different circles of the celestial sphere around the earth. Among them are fixed local references such as the horizon and the meridian plane of the place. The other armillas symbolize the celestial equator, the ecliptic of the Sun, the two polar circles, the two tropics, or the colures (main meridians) of the solstices and equinoxes. They are movable around the axis of the poles also called the axis of the celestial sphere.