A plane drawn through the middle of the earth through its equator intersects this celestial sphere in a circle, which presents as a line called the. When the earth rotates about its axis, the sun appears to move across the sky, causing objects to cast shadows. In order to understand the working of a sundial, it is necessary to have knowledge. Celestial equator, will illuminate the other face of the dial plane. Trigonometry can be used to calculate the positions of the hour lines for vertical and horizontal. In the southern hemisphere the gnomon will point to the south. Equatorial sundial a dial in which the dial plate is parallel to the equatorial plane and the polar-pointing gnomon is perpendicular to it.
If you want to build a sundial that is to work south of the equator you will need to make some changes, but the following method is easy to adapt. Since fosters work, no new kinds of equator projection sundial have been. Thus, the equatorial type of sundial, which has the gnomon parallel to the. Cast by the sun will pass through corresponding positions on the dial and equatorial. If they do not face directly south, they are described as declining dials, and in this. (top right) the equatorial sundial designed by wendy hiller outside the tower. .