E021 Significance of 27 Nakshatra placement

27 nakshatra
A humbling moment!

E021 The Zodiac and 27 Nakshatras: An Astronomical Perspective – Part 5 (Final Part)

Nakshatra placement

In this final part of the series, we will delve into nakshatra placement of 73 taras in ecliptic grid and how their placement has helped to shape a core Indian astrological construct. If you have not read the earlier articles in this series, please get started from my first article to get a better perspective on this series. Bear in view that this article is based on ecliptic grid data.

Kind request

Please do not read this article superficially just the way one would read a daily astrology predictions on newspapers or a WhatsApp forward. If you really want to understand the astronomical principles behind some astrology constructs, pay closer observation to the pictures presented in this article, visualize, make inferences, and then move on. Few gems are kept hidden for the special ones to grab, and I wish all of you to find them 😊.

Nakshatras and their Taras

As stated in my earlier articles, the term ‘Tara’ is being used here to refer to one or collection of stars used to refer 27 nakshatras in Indian astrology. These ‘Taras’ are different from the other commonly used navataras like Janma, Sampat, Vipat etc which refers to a whole nakshatra group.

The collection of taras per nakshatra are presented in the following picture. Nakshatras composed of 2 or more taras are presented below.

Nakshatra Taras
Nakshatra Taras

Significance of the Ecliptic path

Though presented in my earlier article, I feel that the reader will greatly benefit by knowing some additional information here.

Indian astrology is based on Lunar mansions and presence of Moon in a zodiac is given paramount importance. There is a notion that in Indian system, only zodiac signs on Moon’s orbit around the Earth are considered. In other systems, there is a notion that Earth and other planets on ecliptic path of Sun and the 12 zodiac signs on this orbital path are considered. These 2 paths are inclined to each other up to 5.5 degrees. These paths have been picturized below.

There are 2 points at which these paths intersect (consider visually only – the paths of any planets can never intersect with each other) and these two points are 180 degree apart from each other in their orbit. These are referred as ascending node (Rahu) and descending nodes (Ketu) respectively. These two are just mathematical constructs and there is no snake out there.

Astronomy suggests that several million years ago, moon’s orbit was closely aligned with ecliptic path. Complete eclipses were more frequent during those time periods.

Eclipses are given huge importance in Indian astrology. Major worldly changes, including political and other key events are predicted to happen around these eclipses based on the zodiac sign, star, and other planets involved. Many predictions and forecasts that several astrologers make with the recent CoVID-19 pandemic, its reasoning and aftermath falls into this account.

Although eclipses are related to the paths of the Sun and Moon, the discovery that other planets associated with or approaching these ecliptic points of Rahu and Ketu tend to lose their original karakatwas (significance) and yield distorted results to a native is one of the core construct of Indian astrology. At a time when eclipses were amazing and frightening, there is no wonder that people were afraid of them and able to link that phenomenon with human life events.

Magnetic Field

Astronomy says that the Moon, like our Earth and other planets, had a magnetic field of its own at the time of its formation. This magnetic field of earth acts as a bulwark to protect it from the ever-erupting solar wind and debris. Without the protection from this shield (referred as Van Allen Belt) there would be no life on earth.

Astronomy explains that Moon lost its magnetic field due to some astronomical events and subsequently got exposed to series of meteorite attacks, causing craters that appear on its surface. An additional information here is that even Mars does not have such a strong magnetic field like our Earth!

My wild guess is that Rahu Ketu philosophy might have been structured around the possibility of planets with magnetic fields cross each other’s path causing some distorted outcomes.

Since moon’s orbit is the closest (innermost) to earth, it was given higher significance in Indian astrology possibly due to moon’s rapid motion and ability to cause perceptible changes in earth’s weather and tidal patterns. Moon can also completely block view of other planets and many nakshatras on its path (Venus, Jupiter, Mercury also can block view of a star from earth, albeit rarely).

Rahu-Ketu construct is the hallmark of Indian astrology. Behind these points lies some great mystery that can’t be easily and directly explained!

Based on the discussion so far, you would be able to understand and appreciate the importance of the ecliptic path. Stay on!

Ecliptic path of the moon

Let us look at path of the moon in more detail. We saw that this path is inclined up to 5.5 degrees. It has been estimated that the orbit of the Moon around earth in fact can include up to 22 modern zodiac signs, and not just limited to the 12 zodiac signs that lie on the ecliptic path of Sun. This is depicted through the picture below.

22 zodiac, Moon
Rashi, Nakshatra positions on Moon’s Path

This picture validates the strong astronomical knowledge behind Indian astrology. This picture shows 88 modern constellations and their boundaries. The green line in the center of the image indicates the ecliptic path the light blue line indicates path of the moon. All the 12 zodiac signs that we consider in astrology are identified by green colored boxes (numbered from 1 to 12). The other constellations where moon can potentially pass through have been marked with orange colored boxes (10 in number). Just make a note of other zodiac signs marked with a red colored X in this picture. You will understand the reason later.

One of the arguments in astronomy that criticizes astrology for lack of reasoning is why only 12 zodiac constellations have been chosen in astrology, while moon can potentially pass through 22 constellations (see this webpage for more information: https://www.space.com/5417-ecliptic-zodiac-work.html ). Let me provide my argument on this now.

Some Surprising Astronomical Facts

A careful observation of nakshatra positions would reveal that many of these 27 stars lie beyond the boundaries of the 12 zodiac signs. 10 out of 27 stars are not in their astrological zodiac signs. It means that 33 out of 73 nakshatra taras (45% of total) are not placed in the 12 zodiac signs defined for them in astrology!

In the table below, I have listed those nakshatra taras, which are placed outside zodiac signs identified for them.

Nakshatra positions outside assigned constellation
Nakshatra positions outside their assigned zodiac constellation
  • Of these, 9 nakshatras (other than Mula nakshatra), are located in another constellation above or below the particular zodiac sign on the ecliptic grid.
  • Of these nine other constellations, the Moon travels through at least 6 constellations. Please bear in mind that the modern constellation names and boundaries were drawn only after 1930 and we are comparing it with a traditional knowledge, which is several thousand years old.
  • Although the Moon travels through six other constellations (constellations marked with orange boxes: Cetus, Sextans, Auriga, Crater, Ophiuchus and Scutum), those constellations did not consist of any of the 27 nakshatras considered in Indian astrology.
  • Swati, Dhanista (Avittam) and Sravana(Thiruvonam) nakshatra positions do not line up on the path of Moon. However, they have been considered in Indian astrology. You will know the reason behind their selection, towards end of this article.
  • Although Mula nakshatra (#19) is identified against Sagittarius in astrology, it is actually located within asterism of Scorpio.

It may be confusing for an ordinary reader to understand:

  1. If Rashi’s are important, why only 12 out of 22 Rashi’s on moon’s path have been chosen and
  2. Why some nakshatras outside moon’s path have been chosen, if moon’s path is so important for Indian astrology?

Let me attempt to answer those questions now.

Placement of 27 nakshatras on Ecliptic Path

Earlier, we have seen the significance of ecliptic grid and ecliptic path. Based on nakshatra positions data for 2000 AD, if we place all 27 nakshatras in rectangular ecliptic grid, they would appear as shown below. The ecliptic longitude points are on X axis and ecliptic latitude is on Y axis. The map should be read from right to left, in the order of the 12 zodiac constellations.

Nakshatra positions as on Ecliptic Grid
Nakshatra positions as on Ecliptic Grid

The ecliptic grid data is based on western system. But, for Indian system, Asvini is the starting point. Hence, if we adjust the origin to Asvini’s location, this picture can be directly compared against Indian Rashi’s.

Such a view based on adjusted starting point is being presented below (forget which ayanamsa is correct for the time being – that is big topic by itself).

Nakshatra positions on adjusted Ecliptic Grid
Nakshatra positions on adjusted Ecliptic Grid

I consider the above mapping of nakshatra positions as one of my key contributions to knowledge base on Indian astrology. Take some time to review and visualize nakshatra positions of our 27 stars in the sky. Below the image, I have listed 12 zodiac signs, each divided into 30 degrees. Against each zodiac sign, you can see the nakshatra and their position on ecliptic grid.

The ecliptic path and a band ± 6° that can completely covered by moon are shown in this picture. The nakshatras inside this band, can be completely eclipsed by the moon, depending on its inclined path.

Only ten nakshatras out of 27, namely Krittika, Rohini, Pushya, Magha, Chitra, Vishakha, Anuradha, Jyestha, Uttara Ashadha and Revati, fall within the range of this band. Out of 27, a solar or lunar eclipse can occur only with the backdrop of these 10 stars! Eclipses can’t happen astronomically on rest of the 17 nakshatras.

Of these 10, two stars each have been assigned to Sun, Saturn and Mercury. The Moon, Ketu, Mars and Jupiter have one star each. Barely outside of this 6° mark lies Shatabhisha, a nakshatra of Rahu. Therefore, we can consider that at least one star within this ecliptic band have been assigned to the Navagrahas.

We know that all nakshatras are constantly moving on specific directions. Due to this fact, one of the taras of Punarvasu (i.e. Pollux or Diti) will come inside the boundaries of this ecliptic band in few thousand years and could be eclipsed by moon.

If you look at this picture with an astrological lens, you could notice the following key differences.

  • Magha nakshatra is placed within distance boundaries of Cancer.
  • Chitra and Svati are very closely located in terms of ecliptic longitude scale.
  • Mula nakshatra is placed within the range boundaries and asterism of Scorpio.

Distance between Nakshatras

You may be aware that the 360°circle of ecliptic grid is equally divided between 12 rashis (30° each) and 27 nakshatras (13° 20’ = 13.33 deg each). This is a core astrological construct that is behind all calculations and interpretations.

Let us see how the nakshatra taras are located from each other, according to astronomical data in the picture below. The distance between the ecliptic longitudes on the ecliptic grid has been given below as numerical degrees.

Distance between nakshatras
Distance between nakshatras

In this image, two types of data are presented. The pink coloured dots indicate distance between the first taras of two nakshatras. The green colored dots are based on the average distance between two tara clusters. Based on Mean and Standard Deviation data provided in this chart, we can conclude that considering first tara of a nakshatra into our calculations would be ideal.

In the center of the image, an yellow line has been drawn at 13° 20’ (13.33 numerical degrees). A band of 3.33 numerical degrees has been shown, which is considered as distance of one pada of a nakshatra.

In this map, we can see that the nakshatras are spread out on both sides of the astrological definition of 13° 20’ assigned to a star. The following observations can be made from this chart.

  • The sequence of 27 nakshatras as listed in astrological text is exactly matching with astronomical data.
  • Among 27 nakshatras, 16 lie within the band of 3.33 degrees (distance of one Pada).
  • The maximum distance between two nakshatras is ~26° and observed between Vishakha and its previous nakshatra, Svati.
  • Distance between Svati and it previous nakshatra Chitra is the shortest (just 0.4 degrees).

Comparison between astronomical data vs astrological construct:

To find out the extent to which the astronomical data is backing up the astrological construct, let us examine the relationship between them statistically. The astronomical distance between the stars (on X axis) and fixed distance as per astrological construct (on Y axis) are compared in the figure below.

Correlation between astronomical data and astrology construct
Correlation between astronomical data and astrology construct

The diagram and the estimated relationship above confirm that there is a remarkably close correlation between the two. An R2 value closer to 1 indicates that the relationship between them is exact and such relationships are possible only in physics and chemistry. A higher value of R2 is always preferred in the statistical modelling world, to declare the superiority of a model over others. You will not be able to find such a high correlation in any other fields of modeling that deal with human lives. In data science world, a model with R2 value over 0.70 qualifies for celebration!

The image above is a great proof for the advanced astronomical knowledge of our ancestors. Although it may appear at first sight that some 27 nakshatras on different constellations have been chosen, the astronomical reasoning and precision on the distance between the nakshatras is mind boggling and make us speechless! This chart stand as a proof to the strong astronomical observational and measurement skills and reasoning behind astrological constructs. Just show this one chart to those, who question astronomy data behind astrology constructs.


Let me summarize key take-aways of what we have seen so far in this 5-part series.

Behind astrological constructs of 12 Rashis and 27 nakshatras, we could truly see the enormous amount of astronomical knowledge and mathematical precision of our ancestors. Going by this analysis, it is becoming evident that nakshatras have been carefully chosen based on nakshatra positions on moon’s path and distances between them. More importance should be attached to nakshatra positions and distance between them than rashi names. Behind this nakshatra selection, there lies a great mathematical model.

Considered in isolation, data on distance between zodiac signs do not match well with zodiac lengths defined in astrological texts (interpretation derived from part 2). However, when the 12 zodiac asterisms are considered along with 27 nakshatras, their astronomical distances correspond very closely to the astrological construct. This clearly illustrates the uniqueness and supremacy of ancient indian astronomy and mathematical knowledge. I do not know, if there exist such a deep knowledge of astronomy behind construct of other astrological systems.

I am increasingly realizing that it would be more appropriate to position and advance astrology as the field of applied astronomy, rather than as a field based on astronomy proper. In the astrology constructs vs astronomical data comparisons I have attempted so far (For example, this article), direct astronomical data to back up a popular astrology construct yielded inconclusive evidence. This partly reflects the superficial astronomical understanding of present-day astrologers, who do not seem to understand the real astronomy mechanics behind. On the contrary, the astronomical wisdom of our ancestors who applied astronomy behind astrology are very strong and awe-inspiring.

My perspectives:

Instead of making random, superficial astronomy related statements behind astrology constructs, it would be prudent for the modern astrologers with a scientific bend of mind to establish relationships between astrological constructs and astronomy data. This approach could lead us to unearth real reasons our ancestors have stuffed behind several astrology constructs. The field of data science will be an inevitable companion in figuring out the method behind some madness/ unknown things.

Statements like “Planets are responsible for life events” and “Everything is pre-destined already” may help for the sake of arguments, however, can’t be proven with data. Rather than positioning astrology in this crude way (which our ancestors would have frowned upon), it would be better to explain the methods behind astrology to the common man. For example, people would be able to understand and appreciate when they come to know that certain planetary positions and patterns were common with certain life events and interpretations for their life events are made based on this collective wisdom stored in the form of astrological rules.

Staying within these boundaries and making interpretations based on tested astrological rules can greatly enhance the reliability of an astrologer, instill confidence in common man on the subject and can also eliminate unrealistic expectations imposed on astrology as a subject. This approach also offers some room of freedom to an astrologer and help set manageable expectations with their clients.

I offer my sincere gratitude to divine power for guiding me to write this article and fetching me right resources at right times. My thanks are also due to readers like you for your valuable time and spreading this piece of knowledge.

Stay happy and safe!


Astronomy software and data: http://stellarium.org

Broader knowledge base: www.wikipedia.org 

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This Post Has 3 Comments

  1. Sujatha Alluru

    Stunning. This information is astonishing. Very very grateful to you for showing the greatness of our ancestors. Sahastra pranam to your scholarship.

    1. Ramesh

      Thanks for reading and sharing your feedback.

  2. Harish Gopalan

    Very good analysis, research article. Answers many questions and also builds awareness.