See the previous post BUILDING A FOUNDATION OF LEARNING to participate in these free online lessons for learning the basics of Vedic Astrology. Click below to read that post.
https://jyotishamerica.com/2022/12/14/building-a-foundation-of-learning/
Topography of Vedic Astrological Charts

Outline of this Section to be presented in 3 Lessons.
- Two different ways of calculating the Zodiac – Tropical and Sidereal / Understanding the relationship between Astronomical Maps and Astrological Birth Charts as moments in time and space.
- Creating birth charts – Required information and decisions to consider for beginners / The effect of using date, time and place of birth; effects of an inaccurate birth time; methods of clarifying an official birth time; options for a reading when the birth time has been lost.
- The BIG 3 in both the North and South Indian systems / A metaphor for understanding the role, prioritization, and differences between Signs, Houses, and Planets / Why we might choose one system over another.
LESSON ONE – TWO ZODIACS BASED ON METHOD OF CALCULATION
The above image is an antique Planisphere or map of the Northern and Southern hemispheres of the night sky centered on the poles. Modern planispheres have rotating disks that extend outside of the starfield and allow the user to set the date and time in order to establish which direction to look in order to see any specific object. These maps have been used by skywatchers for centuries and modern versions exist as apps that we can carry on our mobile devices. Planispheres are primarily used for identifying constellations, bright stars, and sometimes distant galaxies as well as our own Milky Way. Generally, the printed versions do not have planetary placements but the digital forms often have the whole vault of the sky represented in real time including all of the known planets.
An astrological chart is another form of sky map, focused on the ecliptic, the path the sun travels each year, as viewed from the location of the person or event whose chart we are looking at. The placement of all twelve sun signs, including those hidden below the horizon along with the planets, sun, moon, and the two eclipse points will be indicated. In addition, mathematical points that have special meanings in astrology may also be indicated on the astrological chart.
The birth chart, then, is a symbolic representation of the twelve sun signs in relation to the planets according to the date, time, and place of birth. It is not meant for navigational purposes and is only partially useful for star or planet gazing. Astronomically, it could serve as a rough calendar based on placements of the sun and moon and here we find the first significant difference between the Vedic and Western System.

The images above represent two ways of laying out the Zodiac, the twelve constellations the Sun travels through in a year along the yellow oval called the ecliptic. The upper graphic is the Sidereal Zodiac. It is what is used in Vedic Astrology. The blue oval represents the earth’s equator extended outward to where it intersects the ecliptic at two points on opposite sides of the Zodiac. Sidereal calculation takes account of the known wobble in the earth’s axis of rotation that causes the equatorial intersections to move backward through the Zodiac in a cycle of 24,000 to 26,000 years. This happens because the equator is always at 90 degrees to the polar axis so the wobble (like a top slowing down) changes the intersection point of the equator by one degree approximately every 72 years.
The lower graphic is the Tropical Zodiac as calculated by Greek astronomers approximately 2000 years ago. Although the Greeks probably knew of the wobble in the earth’s axis they did not take it into account in setting up Western Astrology. Consequently, the equator’s intersection point is always said to be at zero degrees of Aries on one side of the Zodiac and zero degrees of Libra on the opposite. These points are the Equinoxes, where the Sun’s crossing puts it directly over the equator at the beginning of Spring and Fall in the Northern Hemisphere (with the seasons reversed in the Southern sky). For this reason, Western Astrology, as established by the Greeks always states that the Sun enters Aries on the first day of Spring and Libra on the first day of fall.
In truth, based on the slow rotation of the wobble, the Sun currently enters Aries on April 15 or 16 each year and Libra on October 15 or 16. The equinoxes still happen in March and September but the Sun is actually just shy of 6 degrees Pisces on the first day of Spring and 6 degrees of Virgo on the first day of Fall in the Northern Hemisphere. This accounts for the 24 degrees of backward movement since the time of the Greeks. Vedic astronomers were aware of this wobble and figured it into all of their calculations centuries and possibly millennia before the Greek Zodiac appeared.
Sidereal astrology uses the actual placement of stars and planets against the constellations rather than basing their locations on a location that was accurate 2000 years ago. For this reason, five out of six people have their Sun Sign in the preceding one from what is commonly presented in Western horoscopes. This is not meant as an indictment of the accuracy of Western Astrology. Just as the placements are calculated differently so too are the meanings attributed to the planets and signs in the Western school different. Both systems work for studying astrology in their own way. However, understanding that unless you were born between approximately the 15th and 21st day of the month following what you identify as your Western Sun Sign, the Sun was actually in the one preceding it in the Vedic system.
To give an example. I was born on the 11th day of June, with my Sun in Gemini according to Western Tropical Astrology. But the Sun actually is located in Taurus in my Vedic chart and that is actually where it was on the day I was born. It didn’t enter Gemini until about three and one-third-days after my birth.
Unlike a Planisphere, which shows the whole map of the sky and uses rotating outer disks to establish directions (East, North, South, and West) based on date, time, and place, a birth chart will show the locations of planets based either on the tropical or sidereal zodiac. Placing planets within constellations, birth charts take into account the latitude and longitude of the birthplace. This makes a person’s birth chart unique. Many charts can look similar or even the same but precise measurement in degrees, minutes, and seconds (all measures of distance in celestial navigation) reveals the differences. In Vedic astrology, these minute measurements, based on the exact location of celestial objects relative to the Zodiac and ecliptic, make a crucial difference in differentiating individuals as we work with the chart and reports generated from them. This will be explained in future lessons.
To end this lesson, the image below shows two birth charts for AA Founder Bill Wilson, one a Vedic Sidereal chart in the North Indian style and the other a chart calculated using Tropical methodology. Note the difference in the Sun’s placement as indicated by the red arrow.
In the Vedic chart (blue) the Sun is at 11 deg 26 min of Scorpio. In the Western chart (circular) it moves to 3 deg 51 min of Sagittarius, a difference of 22 deg 25 minutes.


This difference between the Tropical and Sidereal Zodiac is called the Ayanamsha and increases each year by 48-52 arc seconds due to the wobble in the earth’s axis. As of 2010 the Ayanamsha was 24 degrees, putting the Sun’s actual location at 6 degrees of Pisces on Spring Equinox. Please keep in mind it is not just the Sun moving. The entire system of planets must relocate based on the Ayanamsha. Planets in high western degrees (24 and above) will remain in the same sign. Those below the degree of change will fall backwards.
If you received a birth chart from me, please look at the placement of the Sun for comparison. Did your sign change from the one you commonly identify with? If so, consider what that might mean for understanding your life. There is no right or wrong answer here, but when a paradigm is affected by new information, our sense of who we are based on that paradigm is generally altered. I know that for me moving from Gemini to Taurus, even if I didn’t fully understand the meaning at the time, initiated a major shift in my thinking.
Gemini operates from a language based approach to life. This means it is words that create meaning and engagement for Gemini. Taurus is slower to attach to a life experience, needing time to think through what is being presented and examine it from a practical standpoint. Gemini is flexible and often impulsive, using words to fill out gaps created by its quick intellectual grasp of new material. Taurus compares new experiences to the rules it believes govern life. Until it sees a practical fit, it remains thoughtful rather than engaged in action.
Feel free to discuss your thoughts on this lesson in the comments.