History of Astronomy during the Vedic and Vedang Period

The Begining 

Looking up at the sky is captivating to the human mind. He is naturally attracted to the wonders of the sky. The acquaintance with the stars in the sky is used for guidance for various tasks by people. In fact, very few people would be found in our country who do not possess any elementary knowledge of the sky.

The rising and setting of the Sun, Moon and other planets, onset of seasons, which recur in their regular order is a routine phenomenon. But the ancient man would certainly be wonder-struck with such recurring events in the sky. 

His curiosity to look deeper into the sky, probably led to the Study of Astronomy.

The Sun having disturbed the primitive mind is not a figment of fantasy. Evidence of such primitive thought is found in Jain literature, which shows that they believed in the existence of two suns! The Puranas too postulate 12 Suns. The 12 Aditiyas of Vedic literature are well known.

Today these appear to be fantastic, though the ancient people did cherish such beliefs.

The following verse from Rgveda shows the Sun actually sank in the Ocean before rising the next day.

यहेवा यतयो यथा भुवनान्यपिन्वत ।॥ अत्रा समुद्र आगृद्‌ हमास्‌यंमजभतंन ॥ |

 भ ऋ . सं. १०. ७२. ७.

Meaning- "Oh Gods! you draw out  the Sun which was sunk in the Ocean"

The Following Mantra from Taittiriya Brahman may be similarly cited

य उवगानूमहतोण वादि भाजमानःसलिलस्य मध्यात्‌ । समा वृषभो रोहिताक्षःसुथो विपरिचिन्मनसा धनात्‌ ।!

" May the resplendent Sun, that comes up from the centre of the expanse of water of the vast Ocean, purify me"

This may have prompted him to consider a day (day and night together), a period between two consecutive Sun rises as a natural unit of time.

The ancient man's attention must have been drawn to the Moon as that of the Sun. Unlike the Sun, the Moon does not rise and set regularly and at times just not seen in the sky. Then it appears as a crescent, a newborn Moon. Even to this day, we find people offering frills of garments and praying for new garments and a long life. The following mantra is found in all Vedas.

नवो नवो भवति जायमनोह्लां केतुरुषतामेध्यग्रं । भागं देवेभ्यो विदवात्यायन्प्रचत्रमास्तिरते दीधंमायु : ॥ | ऋ. सं. १०. ८५. १९.

The cycle of waxing and waning of the Moon is 29/30 days. 

Similarly for the Moon, the period between two full Moons is a second but a longer unit of time. In the Vedis literature, the Moon is named a masa. The following lines show us 

सूर्यामासामिथ उच्चरातः । ऋ, सं. १०, ६८, १०. जथ, सं, २०. १६. ११,

RK Samhita and Atharva Samhita

सूर्यामासा विचरता दिवि । ऋ. सं १०. &२ , १२.

RK Samhita 

Once these two units of time were firmly established, he must have observed that rains, summer, and winter recur at definite intervals of time. The seasons, Varsha, Hemanta, Sharad etc. The repetition of the season Varsha was probably used as the word meaning a year. 

The words, Sharad, Hemanta, and Vasant all meaning a year occur in the following verse. Samvtsara is often found to be used in the sense of a year.

शतंजोब शरदो बधंमानः हतं हेमेतांछतम॒वसंतान्‌ ॥

 ` ऋ. सं. १०. १६१. ४. अथ. सं. २०. ६६. €.

" Do live and grow for a hundred autumns, for a hundred winters and hundred springs"

The year then becomes the third natural unit of time, longer than day and month. 

These natural units of reckoning time, guide human activities, depending upon the celestial phenomena.

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Extracts are taken from the Book " Bhartiya Jyotish Shastra-Part I"