JAI PRAKAS YANTRA: Armillary Sphere Instrument

Jai Prakas Yantra


These two complementary instruments display the hourly movement of the Sun and stars in relation to the movement of the Earth around the Sun.

These instruments consist of two hemispherical bowls housed in an octagon. The hemispheres are reflections of the celestial sphere.1 Each bowl contains both open and solid sections; wherever one bowl has a solid section, the other bowl has an open section. The two bowls are complementary to one another and work at alternating hours. The solid "fingers" on each bowl represent one-hour sections of the sky. The upper rim of the bowl represents the horizon. Suspended over the center of each bowl are two crosswires. Directly beneath where the wires cross, at the bottom of the bowl, the zenith point2 is represented. The location of the shadow of the crosswires on the bowl displays the location of the Sun with reference to the celestial sphere.

With this instrument, one can determine the declination,3 altitude,4 azimuth, the rising Zodiac Sign,5 the Zodiac Sign that is on the local meridian,6 the winter and summer solstice, the spring and autumn equinox, and the local solar time.7



The system of the planets revolving around the Sun, the rotation of the Earth on its axis, and the movement of the Earth around the Sun all have an influence on the physiology of the individual. By placing one's attention through the vision on these two Jai Prakas Yantras, those parts of the physiology that are specifically related to these influences coming from outside are enlivened and improved.

1 An imaginary sphere projected into the sky, which surrounds the Earth and takes the Earth's center point as its center. Celestial bodies are imagined as being located on this sphere for the purpose of measuring their positions from Earth for the observer.

2 The point in the sky directly above the observer.

3 The angular distance of a celestial body north or south of the plane of the Earth's equator.

4 An angular measurement from the horizon towards the zenith point.

5 Twelve star constellations that occupy 30 degrees each of the Zodiac circle (a belt around the ecliptic where all the planets orbit the Sun).

6 An imaginary great circle that passes through the north and south celestial pole and the point directly above the observer (zenith point).

7 Solar time differs from local standard time depending on one's location in the time zone, daylight savings, and whether the Earth is nearer to or farther away from the Sun (due to its elliptical orbit). Solar noon is when the Sun is directly overhead.


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