In this lesson you will learn the parts of an astrology birth chart wheel. It begins with two circles, each divided into 12 slices.
The first circle is the zodiac wheel. The 12 slices represent the 12 signs of the zodiac. The inner circle there represents the Earth. In your personal horoscope (your natal chart), that inner circle represents the coordinates, or exact location, of your birth place. We know that, in actuality, the planets revolve around the Sun, but astrology studies how the solar system interplays with us here on Earth. From our viewpoint on Earth, the Sun appears to travel around the Earth, passing through each of the 12 zodiac signs. The Sun spends about one month in each sign, as it travels towards the next sign. The zodiac wheel represents our view of the heavens sliced into 12 sections. Each section measures 30°, with the whole circle measuring 360°. The Moon and the rest of the planets also fit into the zodiac wheel, at the point that corresponds to their astronomical position (which we find in an ephemeris).
Next, the circle on the right represents the 12 Houses, or areas of your life. Each slice (each House) in that circle represents a different area and specific function of your life. They are numbered 1 – 12. The Houses wheel is based on the ecliptic (the apparent path of the Sun around the Earth). The point on the ecliptic that was on the eastern horizon at the moment of your birth denotes the sign and degrees of the beginning of the 1st House in your chart. This is why an exact birth time is vital for an accurate horoscope.
Now, the planets are arranged on the zodiac wheel according to their actual astronomical position in space. Then, that wheel is laid on top of the wheel of Houses. It helps to see this in 3D.
The result is a birth chart wheel that looks like this:
Around the outside edge you see where the zodiac signs fall into the Houses. The slices in the chart represent the House divisions, not the zodiac sign divisions. Here the 12 Houses are numbered. The zodiac sign divisions can be seen along the outer edge of the wheel, represented by different colors.
Notice that the zodiac sign divisions do not line up with the House divisions. It would be rare for that to happen. This is because the joint positioning of the two wheels depends entirely on your exact time and place of birth. Notice though, that the 12 houses are in their original location. The wheel of Houses should always be laid out like this, with the first house on the left; the zodiac wheel (along with the planets in the heavens) is what gets rotated according to birth data. Notice the planet glyphs arranged on the chart, labeled with their degrees of position. The Houses progress counter-clockwise around the chart. The divider line before each house is called its “cusp.” The horizontal line that extends directly left is the 1st House cusp. The degree measurements labeled around the outside edge give the position of the House cusps in relation to the Zodiac wheel.
Four of those cusps have special names (in most House systems). The 1st House cusp is called the Ascendant; the 4th House cusp is called the I.C. (imum coeli); the 7th House cusp is called the Descendant; the 10th House cusp is called the M.C. (medium coeli), or midheaven. You will learn their meanings in a later lesson. For now, you need to know that, of those four, one has extra-special significance. It is the Ascendant, the cusp of the 1st house. The zodiac sign that falls on the Ascendant is called the “rising sign.” The rising sign is very important; it acts like a filter through which the rest of your chart is sifted. The planet that rules the rising sign is considered to be the “chart ruler.” Notice the glyphs for the Ascendant ( ) and the M.C. ( ) in the sample natal chart above. In the chart above, the Ascendant is in Virgo () because the cusp of the 1st house is in Virgo.
You can immediately tell the Rising Sign on a birth chart because it is the sign directly left of the center.
In the sample chart below, the Sun is in Leo ( ); most people would label this person simply as a Leo. But look at the Moon () in the chart; it is in Taurus (). To differentiate further, the Ascendant is in Scorpio (). Here you can begin to see why simply knowing your Sun sign is not enough (and why the popular daily Sun Sign "Horoscopes" amount to a bunch of silliness). To really understand your own natal chart, you must understand all the Zodiac signs because every chart, as you can see, includes the entire Zodiac. The sign on the cusp of each house denotes our attitudes in the department of life designated by that House. Then, any planets in the house also affect our affairs in that area. And of course, the signs that the planets are in will modify how all this is manifested.
You see a number next to each planet glyph. The number tells the exact degree of that zodiac sign in which the planet appeared in the heavens at the moment of you birth (or whatever time the chart is drawn up for). The degrees are taken from an astronomical almanac called an ephemeris. (Real astrology is amazingly mathematical. In ancient days, all real astrologers were also, by necessity, mathematicians. Nowadays, great astrologers can use computers to calculate birth charts, allowing them to focus on reading & interpreting the chart.)
In the example below, the lines in the center are marking the aspects between planets. Aspects will be discussed further in a later lesson.
To sum up, the natal chart is your horoscope. It is a map of the heavens at the moment you were born, from the viewpoint of your birth coordinates. The birth chart wheel is composed of a zodiac wheel containing the planets, positioned amongst a wheel of 12 Houses, and you are at the center.