About Astrological Charts

The first thing that one notices about an astrological chart is that it takes the form of a circle. This circle represents the ecliptic, the path that the sun travels on as seen from the earth. The twelve signs of the zodiac all fall along this path. In modern astrology, we treat each sign as if it takes 30° of the circle, although the constellations are of varying size.

The planets may fall above or below this line through the sky at any given time. In order to create a chart, all of the planets are mapped onto the ecliptic in the position and sign that they are in, although celestial latitude (the distance north or south from the ecliptic) is sometimes used for other calculations.

The chart is also oriented in terms of the position of the stars at a given time and place. The horizontal line that transverses the chart–the ascendant/descendant line–represents the horizon, with the left hand side being the east (the ascendant or rising sign) and the right hand side being the west (the descendant).

The chart also takes note of what falls directly above us, the Midheaven, at the top of the chart (the tenth house cusp on most house systems), and what lies directly below us (through the earth), the Imum Coeli, at the bottom of the chart.

Starting at the ascendant, and counting counter-clockwise, the chart is broken up into twelve houses. There are many ways of determining where these houses fall, but most rely on finding the midheaven and ascendant and then working out the houses from those. Others, which in my experience do not work well, use a system of dividing the houses equally across the chart.

The Birth Chart

The most common type of chart in modern times is the birth chart. This chart looks at a representation of the sky at the time of someone’s birth. This chart can give a clear picture of what the individual’s basic personality is like throughout his or her life. It also can tell what some of the major issues that he or she will face over the course of life, and how he or she will best be able to deal with them in fitting with his or her personality.

This chart is the basis for all other charts, and careful attention to the details surrounding it are extremely important. An accurate birth time and location are necessary in order to determine houses and ascendant/descendant. Also, while knowing that someone was born on a particular day can tell quite a bit about him or her, some of the faster moving celestial bodies–such as the Moon–may change sign or house in the course of a few hours (or even a few minutes), so their entire influence could be colored differently, especially in terms of aspects.

Other Charts

There are many other types of charts that are important to modern astrology. Most of these rely on an accurate birth chart in order for them to be useful.

Progression

Used to show the major trends going on in an individual’s life at a given time, a progression chart takes the birth chart and advances it at a rate of one year equals one day. This symbolism works very well for long-term trends and long-range planning. In general, a progression chart is only necessary once per year.

Transit

For shorter term planning, transits–the current position of the planets in the Zodiac as they relate to the birth chart–are used. The influences of the planets as they pass over, or aspect, the position of our natal planets can be felt in usually minor trends that last only a short time–hours to months depending on the speed of the planet.

Relationship Charts

In addition to calculating a “birth chart” based on the moment of a relationship’s beginning, there are two other techniques which are useful for determining the various aspects of a relationship. The two most common types of charts used for evaluating relationships for their general tone and “personality” are slightly different in their methods, and thus their application:

Synastry

Synastry is used to compare two birth charts side-by-side or, more commonly, on the same chart. The aspects between the various planets and angles between and within the charts are calculated, and then the charts are evaluated.

This method is useful for seeing how two people interact with each other as individuals. Generally, this method is only employed for two-person, dyadic, relationships. This is because of the labor-intensive process involved in evaluating the charts of more than two people.

Composite

The Composite chart calculates an effective position of planets and houses for the relationship as a whole. This is done by comparing the planetary positions of the two–or more–people involved, and creating a chart based on these. This technique tends to give a feeling of how the people involve behave as a couple or group, without focusing on their individual reactions. This process is commonly used for couples, as well as larger groups, such as offices or partnerships.

Electional Charts

Electional charts are used to select a time or date for a given event–wedding, business venture, etc. The process, similar to calculating transits for a future event, involves choosing between various options for the one in which the energies of the planets are most in tune with the desired effect.