The Vriddha Yantra is primarily used to measure the altitude of celestial bodies above the horizon.

The Vriddha Yantra was first invented in the 5th century BCE by the Indian astronomer Lagadha.

The Vriddha Yantra operates on the principle of reflection, where the light from a celestial body is reflected off a mirror and then observed.

The Vriddha Yantra is typically constructed using wood and metal, with a mirror made of polished metal.

The Vriddha Yantra is typically shaped like a circular disc, with a mirror mounted at the center.

The Vriddha Yantra is used to measure the altitude of a celestial body by observing the angle between the celestial body and the horizon.

The main advantage of using a Vriddha Yantra over other astronomical instruments is that it is easier to use.

One of the limitations of the Vriddha Yantra is that it can only be used to measure the altitude of celestial bodies.

Some of the famous astronomers who used the Vriddha Yantra include Aryabhata, Brahmagupta, Bhaskara II, and Varahamihira.

The Vriddha Yantra has great significance in the history of astronomy, as it was the first instrument used to measure the altitude of celestial bodies, it was used to make accurate observations of the planets and stars, it helped to develop the science of trigonometry, and it was used to create the first star charts.