How is an Astrology Chart Structured? An Introduction

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When you first approach your birth chart, you are confronted with a circular “map” containing various lines and symbols. In this article, we will walk through the main components that you will need to understand how an astrology chart is structured. A key aspect of being able to “read” or synthesize your birth chart is having an understanding of how the map is laid out.

We will be covering the following:

  • Intro to the Zodiac and Its Origins
  • The 360 Degree Circular Shape of the Chart
  • The 4 Major Angles
  • Houses + Systems
  • Reading Astrological Symbols
  • Putting It All Together


The Brief Origins of the 12 Sign Zodiac We Use Today

The zodiac is composed of a 360 degree imaginary band in outer space from our perspective as viewed here on Earth. The concept was first developed by ancient people’s observation and tracking of the movement of the planets against the backdrop of the constellations. The origins of observing the planets, eclipses and other astrological phenomena can be traced back to ancient Babylon and Sumer. Later from 300 BCE up through 150 AD, ancient Greek scholars further developed their inherited astrological techniques from ancient Babylon. Many of these techniques are still utilized today for calculating and structuring the astrology chart!

The zodiac sections and the 12 signs we know today were named for the constellations that could be seen occupying the particular area of the sky at the time. Today, due to the procession of the Equinox, the constellations are not directly in the signs that the zodiac was originally named for. Despite this fact, Western Astrology still relies on this ancient system.

From a spiritual perspective, although not astronomically precise, the system still somehow produces very accurate information. It is possible that enough collective energy, mythos, and intention has been placed into this system that it would appear other magical or spiritual elements are operating on an intuitive and esoteric level to make it work. This is one aspect of astrology that makes it such a special and unique exploration of the soul!


Why is the Chart a Circle?

You may have noticed that an astrological chart is a perfect circle. From a surface perspective, this is due to the fact that we are observing the circular movement of planets as the Earth rotates and moves through space. On an esoteric level, this could be due to the fact that astrology often views life as cyclical as opposed to a linear experience. Life contains cycles that repeat, some that take lifetimes, and events or memories that are contained and viewed better within the framework of a circular pattern.

The 360 degrees of the circle contains each of the 12 signs of the zodiac at 30 degrees each. This structure is the foundation in understanding your own birth chart. When you look at your chart you can see that you contain each of the signs equally! You are a whole person made up of multiple twists, turns, and seeming contradictions.

In addition to the signs, another layer of meaning is added to the circular chart using what is called the angles and houses. These areas of the chart add direction and further structure to the map.


The 4 Major Angles: The Ascendent, The Midheaven, The Descendent, The Nadir

An astrological chart is like a compass. It is sectioned into four quadrants with a north, south, east, and west so to speak. These 4 angles create a cross shape in the chart that can help identify the significance of a particular planet in that region of the sky at birth. Let’s start with the Ascendent as this may be the most familiar.

Ascendent (ASC)

Due to the fact that the chart is a view of the sky from Earth, the Ascendent is actually on the left hand side of the chart which is referred to as the Eastern quadrant. This is the sign that was directly on the horizon at birth and where its alternate name, Rising sign, comes from! This line will fall in the First House or be contained within the First House depending on what House System you are using (explained further below).

The sign on the first house or the Ascendent is extremely important in that it gives you the placement within the rest of the chart of the rest of the signs on the wheel of the zodiac. The order of the signs does not change but are placed on the chart using the Ascendent calculation.

Symbolically this part of the chart helps set up your personality, your physical characteristics, and personality traits you wear on the surface. Any planets in this area of your chart tend to be pronounced and expressed more prominently in life. Everything below this line was below the horizon at the time of your birth; meaning it will be expressed in a more personal, identity oriented way.

The MidHeaven (MC)

Second most important angle is the Midheaven. This is at the very top of your chart and is calculated based on the Sun’s perceived path through the sky marked by its highest point in the day. This area of the chart tends to be associated with your most public persona. It can be in the 9th, 10th, or 11th house again depending on the house system you are using. The Mid-Heaven can help illuminate possible career paths, moments of prominence, and assist in predicting when major shifts will happen in your public life.

The Descendent (DC)

This area of the chart is located exactly opposite the Ascendent or rising sign and will start or fall within the 7th house. In the 7th house, we are working with the energy of opposites and awareness. In this house, we start to encounter areas of life, personality, and experience that are outside of us. This is the reason this house is often associated with relationships.

The Descendent is symbolic of parts of ourselves that we are working on integrating or learning more about. We may be learning through others and the outside world with a desire to gain a deeper understanding of the things we are not. It can represent relationships of all kinds and the variety of experiences you have in your encounters with others.

The Nadir (Imum Coeli or IC)

The Nadir or IC is located exactly opposite the Midheaven. It is symbolic of the area of your chart that is your most private aspects of self. Planets on Nadir often call for deep psychological exploration and require effort in drawing out their significance in your life. The sign you have near this important angle in your chart lends you insight into the parts of yourself you will show to your closest friends and family. It can provide you with information on the aspects of self you may be too shy to share with the world. The Nadir is a very vulnerable and valuable area of the chart to explore psychologically.

The 4 angles create important dividers within the context of the chart. This cross often helps set up the house system and the rest of the chart structure. The signs and planets that fall within these quadrants formed speak to the nature of their expression in the overall snapshot of your chart.


Try This! Get a copy of your chart to see if you can find any of the planets near these prominent points in your chart!


The Houses + Systems

After you map out the angles you will notice that the chart is further divided into more sections, which are called houses. The houses are symbolic of the areas or themes of life the signs and planets are operating through. For example, the 9th house is symbolic of travel and higher education. Having multiple planets in the 9th house could indicate that either frequent movement or getting a degree are very important aspects to your life journey!

Whereas many Astrologers agree upon the use of particular symbols and meanings for the planets, signs, and aspects; the houses are a little different. There are multiple systems and mathematical calculations that can be used which create different house system patterns! Depending on what house system you decide to use it can move your planets from one house to another. It is important to note that the house system as no effect on the location of the planets in the signs.

The houses are 12 sections created within the circle of the chart. Traditional, classical techniques, use an equal or whole sign house system. This means each house is exactly 30 degrees each containing its own complete zodiac sign. Other house systems, such as Placidus, calculate particular points in your chart based on the location of the time of birth. These systems calculate the houses around Ascendent Sign or the Midheaven.

The houses can line exactly up with the zodiac signs or vary based on particular mathematical calculations. Due to the houses being a later addition to the horoscope and astrological chart as advancements in tracking instruments developed, various astrologers, developed different systems for calculating where the 12 houses should begin and end.

There are countless house systems and people tend to use the one they are trained in or feel most drawn towards. Here is a list of house systems frequently used in astrology:

  • Campanus
  • Placidus
  • Regiomontanus
  • Porphyry
  • Koch
  • Equal
  • Whole


Astrological Symbols

Now that you know the map is laid out into a circle containing divisions through angles and houses it is time to understand the purpose of all of the symbols placed on the chart!

Each planet, zodiac sign, and aspect (mathematical relationship between planets) can be written using a symbol. This can feel like learning a new language when you first start to dive into understanding your own birth chart! The use of symbols in astrology is essential to understanding the chart. Each of the symbols are representative of multiple correspondences including; elements, modalities, specific mythologies, archetypes, and keywords.

Getting to know the meaning behind the astrological symbols in your chart is one of the most important steps in learning about astrology!

Just as when you start to learn a new language, you begin to create new roadmaps in your mind that will lead you to pertinent information in synthesising and knowing your chart more deeply. Working with keywords associated with each symbol is an excellent way to start to associate the various symbols with particular meanings.


Putting It All Together

As you begin to get familiar with reading the structure of the chart you will start to be able to identify the symbols on the map. For example, the symbol represented by the Sun = ☉ and maybe your Sun sign is Taurus = ♉︎. When you look at the chart you can find the symbol for the Sun and see that it is in the sign of Taurus. This is how you discover where each planet is located in which sign throughout your chart. You are one step closer to being able to decipher the code and language of astrology!

After discovering the location of your Sun sign, you may notice it is right near the Midheaven at the top of your chart. This will then give you further insight into mapping out your chart. You now know that not only is your Sun sign in Taurus but it is in the most public area of your chart! This is just one example of how to start to synthesize and put together all of the pieces of the chart structure.

When learning astrology it can be very helpful to draw out your own chart and start to place the symbols in the proper locations. This will start to help you understand the intricacies of the sky at the exact time of your birth. An alchemical process seems to take place in the discovery and deeper exploration of your chart. Psychologically, pathways seem to be formed within your mind, opening you up to the cyclical and shifting nature of the astrological experience!

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