Surya Siddhantha Measured Time Before Modern Clocks — by Yogesh Tiwari

 Long before digital clocks and atomic

 watches, ancient Indian astronomers had already developed a sophisticated method to measure time — down to fractions of a second. The text at the heart of this precision? Surya Siddhanta, a 1,500+ year old Sanskrit astronomical treatise.

In this post, we’ll explore how this ancient system measured time using the sun, stars, and mathematics — and why it still deserves our attention today.

🌞 What is Surya Siddhanta?

Surya Siddhanta is an ancient Indian text on astronomy and timekeeping. It offers detailed methods to calculate:

• The positions of planets
• Sunrise and sunset times
• Eclipses
• Sidereal time (stellar time)
• The Earth’s rotation and inclination

Far from being mythological, this is a mathematical astronomy manual, written in verse

🕰️ Timekeeping Before Clocks

Surya Siddhanta divides time into the following units:

Unit	Meaning
Truti	~29.6 microseconds
Nimesha	Blink of an eye (~0.213 seconds)
Kshana	1 second
Kala	1 minute
Ghatika	24 minutes
Muhurta	48 minutes

There are 30 muhurtas in a day. This system could calculate sunrise and sunset with surprising accuracy, just using the observer’s location and solar position.

🧭 Ujjain: The Prime Meridian of Ancient India

Surya Siddhanta considered Ujjain (Madhya Pradesh) as the reference meridian — just like Greenwich is for the modern world. All planetary calculations were aligned to this ancient Indian “zero longitude.”

Why Ujjain? Because it lies almost on the Tropic of Cancer and was central to Indian trade, religion, and mathematics.

🌍 Why It Still Matters

• Modern astronomy software confirms that Surya Siddhanta’s sunrise/sunset predictions are within a few minutes of today’s tools.
• It gives insight into cyclical time and Earth’s motion, offering a different but mathematically sound worldview.
• It reminds us that knowledge and science thrived long before colonial influence or European clocks.

🔍 What’s Next?

In future blogs, I’ll explore:

• Day Light saving alternative and Time Zone Calculation Using Surya Siddhanta with Ujjain as the Prime Meridian 
• How to calculate your own sunrise time using Surya Siddhanta
• Why the Tropic of Cancer plays a key role in ancient Indian astronomy
• Can AI simulate Surya Siddhanta’s logic?