## Discovery of the Original Boundaries of Nakshatras

# Zero Points of Vedic Astronomy

## Part 3 of 8 — The Clock in the Sky

In my previous article I showed that the original boundary of the beginning of the Aśvinī nakṣatra was at 8° from Hamal, the yogatārā of Aśvinī. The boundary of the beginning of the Aśvinī nakṣatra was later shifted to the yogatārā of Revatī in sixth century. These two points are separated by 10° as shown in Figure 1, point A being the original boundary of the Aśvinī nakṣatra and point R being the currently accepted boundary. These two points are related to the yogatārās of Rohiṇī and Kṛttikā nakṣatras.

**1. Rohiṇī system**

The span of each nakṣatra is 13° 20′. The span of three nakṣatras equals 40°. Point A is 40° away from Aldebaran, the yogatārā of Rohiṇī. Thus I have proposed that the yogatārā of Rohiṇī was at zero longitude of the original nakṣatra system [1, 2]. I have named the coordinate system with origin at the yogatārā of Rohiṇī as the Rohiṇī system, which is shown in Figure 2. The ecliptic longitude of the yogatārā of Rohiṇī, Aldebaran, was 0° 0′ on June 12, ‑3044 according to Stellarium software. This is close to the traditional date of the beginning of Kaliyuga in 3102 BCE. In the Rohiṇī system, the yogatārā of Rohiṇī is at the beginning of Rohiṇī nakṣatra and subsequent nakṣatras are at 13° 20′ from this point. Zero points of Vedic astronomy in Rohiṇī system correspond to the position of vernal equinox at nakṣatra boundaries in Rohiṇī system. As the position of vernal equinox changed due to precession, first nakṣatra in the list was changed from Kṛttikā to Bharaṇi and then to Aśvinī. Based on the boundaries of nakṣatras as illustrated in Figure 2, the dates for the position of sun among the nakṣatras during equinoxes and solstices can be calculated. These dates are shown in Figures 3 and 4 and can be used for dating of ancient Indian texts. During first millennium, there were attempts to shift the boundaries of nakṣatras to take into account the movement of equinoxes due to precession and keep the calendar in tune with the traditional understanding of lunar months. This resulted in the development of another coordinate system that I have named Kṛttikā system [1, 2].

**2. Kṛttikā system**

Point R in Figure 1 is 40° away from Alcyone, the yogatārā of Kṛttikā. I have named the coordinate system with origin at the yogatārā of Kṛttikā as the Kṛttikā system, which is shown in Figure 5 [1, 2]. In the Kṛttikā system, the yogatārā of Kṛttikā is at the end of Kṛttikā nakṣatra and subsequent nakṣatras are at 13° 20′ from this point. Based on the boundaries of nakṣatras as illustrated in Figure 5, the dates for the position of sun among the nakṣatras during equinoxes and solstices can be calculated for the Kṛttikā system. These dates are shown in Figures 6 and 7. Currently, ancient Indian texts are dated using this system, which are approximately seven centuries later than the dates in the Rohiṇī system.

The concepts discussed in this article are also important for calculating the true value of ayanāṃśa, which will be discussed in the next article.

**References**

1. Roy, R.R.M. (2019). Sidereal Ecliptic Coordinate System of Sūrya Siddhānta, Indian Journal of History of Science, 54(3): 286–303.

2. Roy, R.R.M., 2020. Zero points of Vedic Astronomy. Mississauga, Ontario, Canada: Mount Meru Publishing.

**More about the author**

I am a seeker in search of the true history and heritage of India. I have strong scientific background (B.Tech. in Metallurgical Engineering from Indian Institute of Technology, Kanpur and Ph.D. in Materials Science and Engineering from The Ohio State University, USA) and a deep interest in ancient Indian texts. My work on Indology spans three different fields: cosmology, astronomy, and history.

**Email:** rajarammohanroy108@gmail.com

**Next: ****Zero Points of Vedic Astronomy: Part 4 of 8 — Introducing Ashwini Paksha Ayanamsha**