365DaysDate: April 19, 2009


Title: Ancient Indian Astronomy

Podcaster: Harith, Rahul, and Rohith

Description: According to the Vedas, the holy scriptures of Ancient India, the birth of Indian astronomy dates to around second millennium BCE. India, who made the first mark in astronomy, had significant influence on other civilizations’ development in the field. Since then, the world witnessed gigantic leaps in Indian astronomy which brought India to her current position in space research. This podcast attempts to explain the Who, What, When, Where and How of Ancient Indian Astronomy.

Bio: We are a group of friends with a common interest in astronomy. We wish to take this interest to the next level by participating in activities like this and also help others appreciate our universe better.

Today’s Sponsor: This episode of “365 Days of Astronomy” is sponsored by Astrocamp Summer Mission of Idyllwild, California. Help introduce a child to the world of Astronomy. Learn more at www.astrocamp.org.


Hello and welcome to the three sixty five Days Of Astronomy programme’s hundred and ninth podcast. This is Harith, Rahul and Rohith. We are a group of friends from Hyderabad, India with an interest in Astronomy. 34 years ago on this very day, India launched its first satellite Aryabhatta. It was named after one of the pioneers of Ancient Indian Astronomy which will be our topic of discussion.

Indian heritage and culture are influenced by the Vedas.

‘What are the Vedas?’

The Vedas are among the oldest scared texts in the world. The Vedas were born around five thousand years ago during the transition of the world from the Neolithic Age to Bronze Age. In those days, knowledge was imparted to the next generation through recitations because they lacked a persistent storage medium like paper. So, though you may find some sources citing the oldest Vedic manuscripts dating back to 1500BC, you should keep in mind that they were in existence well before that.

The oldest mention of astronomy in India dates back to second millennium BC and has been found in the Vedas. In Indian languages, the science of astronomy is called “Khagola-Shastra”. The word Khagola refers to the “cosmos” and Shastra means “Science”.

‘So, what motivated the people of those times to study the cosmos?’

The Bronze Age marked the beginning of agrarian civilizations. The first farmers needed to keep track of the seasons but had no formal way to do it. Indians, one of the oldest civilizations in our world, looked up towards the sky and noticed that a clock was staring at their faces.

The Ancient Indian astronomical works are generally divided into two classes. One class were alleged as revelations. The authors hid their names with the definite motive of making their astronomical theories and calculations acceptable to the common man. By doing so, they made them look like direct transmissions from the Gods. In Indian Mythology, seven Celestial bodies were believed to be around our Earth. They were the Sun, Mercury, Venus, Mars, Jupiter and Saturn. Only these bodies were considered because only these objects appeared to be in motion relative to the other “dots” in the sky. There were two other “evil” bodies, Rahu and Kethu, which were said to be “invisible” and would make the Sun disappear once in a while.

‘Yes, you guessed it right. These are references to solar eclipses. In fact, prehistoric Indians were able to predict these occurrences precisely!’

A few excerpts from the Vedas can give us an idea of how advanced the Ancient Indian Astronomy was. For example, an old Sanskrit verse goes like this – “Sarva Dishanaam, Suryaha, Suryaha, Suryaha”. It translates to, “There are Suns in every direction”. We now know that the Sun is a star. So the verse can be interpreted as their realization that all stars in the night sky and the Sun were similar. Also, the Sanskrit term for gravity is “Gurutvaakarshan”, the roots of which are “Guru” and “Akarshan”. Guru means “Master” and Akarshan “Attraction”. The term Gurutvaakarshan means “to be attracted by the Master”. The usage of Gurutvaakarshan in this context can be interpreted as a support to the recognition of the Heliocentric and Gravitation theories. Since, the term Guru corresponds to the male gender, it could be attributed to the Sun which was considered as a male, and not the Earth which was always referred to as a female. Unlike Newton who questioned why the apple fell down and hypothesized that it may be that the Earth attracted everything, ancient Indian astronomers realized that the Sun attracted the planets. They realised that, things not only fall towards the Earth but also towards the Sun.

The second class of these works were relatively new. The major contributors were distinguished astronomers like Lagadha, Aryabhatta, Bhaskara, Varahamihira, Brahmagupta and others. Surya Siddhanta, which was written by the Indian astronomers in 5th century, has explicit mentions of the discovery of the Heliocentric and Gravitation theories.

‘And what did these astronomers do?’

Around 1200 BC, Lagadha, in his work VedƒÅnga Jyotishya, listed several important aspects of the time and seasons, including lunar months, solar months, and their adjustment by a lunar leap month called Adikamasa; Adika means “Extra” and Masa means “Month”. Basically, after every 6 years during which a month spanned about thirty days, an extra month would be added to the calendar. Later Aryabhatta, in his book Aryabhatiya, mentioned that the Earth rotates about its axis, thereby causing what appears to be an apparent westward motion of the stars. He also mentioned that moonshine is reflected sunlight. Aryabhata wrote that 1,582,237,500 rotations of the Earth equal 57,753,336 lunar orbits. This is an extremely accurate fundamental astronomical ratio (1,582,237,500/57,753,336 = 27.3964693572), which is the lunar cycle, and is perhaps the oldest astronomical constant calculated to such precision.

‘And here is the icing on the cake. Aryabhata discovered these facts 1,500 years ago, that is, 10 ten centuries years before Copernicus and Galileo, the pioneers of European astronomy.

But they surely could not have made such precise calculations and observations without the help of instruments. Instruments like Clepsydra, Star clock and Gnomons were prominently used for determining time and seasons. It is generally accepted that gnomics is the oldest device to measure time and was invented by Indians. Gola yantra, also known as the armillary sphere, was used for observation in India since early times, and finds mention in the works of ƒÄryabhata. Another fellow, by the name Bhaskaracharya, calculated the heights of terrestrial objects with the help of a long stick placed along the diameter of a semicircular disk. This disk had angular graduations and a pivoted chain at its center. This is basically the description of a sextant. In 12th century, Bhaskara II invented a device called ‘phalaka yantra’. It consisted of a rectangular board with a pin and an index arm and was used to determine time from the sun’s altitude. A device named ‘KapƒÅlayantra’ was an equatorial sundial instrument used to determine the sun‚Äôs azimuth.

To sum it all up, India who made the first mark in astronomy, had significant influence on other civilizations’ early development in the field. Due to lack of telescopes, Indians could not make any significant progress. Nevertheless, even after centuries of stagnant research, India is catching up with the leaders of space technology.

End of podcast:

365 Days of Astronomy
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