Nadivalaya PDF Print E-mail
Written by Yogesh Soman   
Sunday, 26 March 2006 01:02

A Nadivalaya consists of two circular plates fixed permanently on a masonry stand of convenient height above the ground level. The plates are oriented parallel to the equatorial plane, and iron styles of appropriate length pointing toward the poles are fixed at their centers. The instrument is an equinoctial sundial built in two halves, indicating the apparent solar time of the place.

The Nadivalaya is an effective tool for demonstrating the passage of the sun across the celestial equator. On the vernal equinox and the autumnal equinox the rays of the sun fall parallel to the two opposing faces of the plates and illuminate them both. However, at any other time, only one or the other face remains in the sun. After the sun has crossed the equator around March 21, its rays illuminate the northern face for six months. After September 21, it is the southern face that receives the rays of the sun for the next six months.



Last Updated on Sunday, 26 March 2006 01:04