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Sayana Acharya and the Speed of Light in the Rigveda

There are moments in history when science and spirituality seem to meet at a mysterious crossroads. One such wonder comes from 14th-century India, where the great Vedic scholar Sayana Acharya, minister and commentator in the Vijayanagara Empire, left behind a statement in his commentary on the Rig Veda that has astonished modern thinkers for generations.

The Remarkable Verse

In his exposition on Rig Veda 1.50.4—a hymn in praise of Surya, the Sun—Sayana writes:

 “तथेमे सूर्यस्य रश्मयः निमेषार्धेन योजानानि द्विसहस्राण्येकविंशतिः च यान्ति।”

Tathemé Sūryasya raśmayaḥ nimeṣārdhena yojanāni dvisahasrāṇyekaviṃśati ca yānti.

“The rays of the Sun travel 2,202 yojanas in half a nimeṣa.”

On the surface, this seems a poetic image describing the Sun’s swift light. But when those ancient measures are converted into modern units, the result is astonishingly close to the speed of light known today.

To understand this claim, we must first decode the two units used by Sayana Acharya:

1. Yojana — Measure of Distance

A yojana is an old Indic measure of length. Depending on the period, its value ranged between 5 and 9 miles.

For astronomical calculations, it is most often taken as about 9 miles (≈ 14.5 km).

2. Nimeṣa — Measure of Time

A nimeṣa literally means a “blink of the eye.”

Traditional texts describe:

1 nimeṣa = 16⁄75 of a second ≈ 0.213 s.

Therefore, ½ nimeṣa ≈ 0.1065 seconds.

 Calculation

Given:

Distance = 2,202 yojanas

Time = ½ nimeṣa

Convert to modern units:

1. Distance:

2,202 yojanas × 9 miles = 19,818 miles

2. Time:

½ nimeṣa = 0.1065 seconds

3. Speed:

19,818 miles ÷ 0.1065 s = ≈ 186,000 miles per second

That figure is practically identical to the modern measured speed of light—186,282 miles per second (≈ 299,792 km/s).

How could a 14th-century scholar arrive at such a number?

Interpretations vary:

1. The Traditional View

Some believe Sayana was recording knowledge preserved from far older Vedic sources—perhaps insights of ancient astronomers or seers who perceived cosmic principles through intuitive or observational means.

2. The Scholarly View

Others suggest the statement was a poetic hyperbole, expressing the divine swiftness of sunlight rather than a literal measurement. The apparent accuracy could be a numerical coincidence, since ancient units like yojana and nimeṣa varied greatly across regions and eras.

The Rig Veda’s 50th hymn in its third mandala is dedicated to Surya, the source of life and illumination. It praises the Sun’s brilliance and the spread of his rays through the cosmos. Sayana’s comment thus belongs to a spiritual and philosophical framework rather than a laboratory context.

Yet, his choice to quantify the motion of sunlight shows that Indian thinkers had already begun linking cosmic divinity with mathematical description—a mindset that later inspired India’s long tradition of astronomy, from Aryabhata to Bhaskara.

Whether coincidence or conscious calculation, Sayana Acharya’s words remind us of the deep curiosity and intellectual precision that existed in India long before the modern scientific era. His commentary stands as a bridge between Vedic symbolism and scientific inquiry, proving that observation, wonder, and reverence can coexist within a single verse.

 “The rays of the Sun travel 2,202 yojanas in half a nimeṣa.”

— Sayana Acharya, Commentary on Rig Veda 1.50.4

When translated into today’s language of physics, this gives the speed of light—a value incredibly close to modern science.

Whether by coincidence, preserved wisdom, or sheer brilliance, Sayana Acharya’s insight continues to evoke awe, pride, and respect for India’s ancient pursuit of cosmic truth.