ecliptic

ekliptika puhekieltä The apparent path of the Sun in the sky. More accurately, it is the intersection of the celestial sphere with the plane of the ecliptic, which is the geometric plane containing the mean orbit of the Earth around the Sun. So named because an eclipse can occur only when the Moon lies on this plane.
puhekieltä A great circle drawn on a terrestrial globe, used for illustrating and solving astronomical problems.