Tonight I want each of you to have a chart in front of you on paper. What chart it is doesn�t matter. It can be your natal chart, or a chart for this moment, or whatever chart you can grab quickly to look at and write on.
The word horoscope come from a Greek word that means hour-marker. A horoscope is literally a picture of the sky frozen at a particular moment from a particular place. First, let us get our bearings. Imagine we are standing on the earth, facing south (the direction of the sun�s culmination for the northern hemisphere). To our left, the sun rises in the east. Ahead of us, he culminates in the south. To our right, he sets in the west. And behind us he reaches the bottom of the sky and begins the ascent towards dawn once more. Now look at a chart. The ascendant is to the left, the midheaven is at the top, the descendant is to the right, and the nadir is to the bottom. These four locations mark the angles of the chart. They are the same in every house system (of which there are many). Imagine these lines extending all the way into space out to the zodiac. The signs that these lines land in are said to occupy their respective angles.
If we draw lines connecting opposing angles, we have divided the chart into its four quadrants. Now we divide each quadrant into thirds and this gives us twelve wedge-shaped sections to our chart. Each of these sections is called a house. These 12 houses correspond to the 12 signs of the zodiac. How we divide the quadrants is based wholly on what house system we choose. There are many formulas for calculating these houses, all based on slightly different logics. Some are space-based, that is, they are based on the visual distance between the angles and the specific signs that occupy them. Some are time-based, that is, they are based on how long it takes a particular sign to cross a certain portion of the sky. Some are based on common sense, that is, based on a logic that is readily apparent when one looks at the chart. To the best of my knowledge, all house systems have their pros and cons. Choosing which house system to use is like choosing which TV model to buy. Each one will get the job done in its own way.
I do not bother to go into the elaborate trigonometry that is used to calculate each house system, any more than I study the electronics in my television. As long as it works, I don�t care how. I�m sure there are websites I could visit and books I could read to learn more about them, but I don�t need to do it to be a competent astrologer. That�s what software and tables of houses are for. Some of the more popular methods today are Placidus, Koch and Campanus. I have no experience with any of these. The ones most popular in medieval days were Alcabitius and Regiomontanus that I know of. In the ancient world, whole sign, equal sign, and Porphyry were usually used. Personally, I use Regiomontanus. It is what Lilly uses, and thus what I was taught. It is what all my friends use, which makes it much easier to discuss a chart. In the interest of consistency, I have asked you all to set your own software to Regiomontanus as well. It would cause way too much confusion if I used Regio houses and got a 2nd house cusp of 3 Leo, and someone else used Porphyry and got a 2nd house cusp of 28 Cancer.
Regardless of my apathy towards trigonometry, it is useful to understand the concepts of the anciently favored house systems. Let us look at whole sign houses first. Let us say that our chart has an ascendant that falls in Gemini. All house systems are derived in one way or another from the ascendant.
Q: How do you use two different methods and end up with two very different answers?
A: It is because each house system has slightly different trigonometry involved.
In whole sign houses, the entire sign of Gemini is the first house. We then follow around in a counter clockwise manner to determine the rest of the houses. So the second house is the sign of Cancer. The third house is the sign of Leo, and so on and so forth around the chart. This is logical. It makes intuitive sense. It is still incorporated today by many brilliant astrologers. Equal sign houses are a bit more precise. They mark the actual degree of the ascendant and count from there. So if our ascendant is specifically 5 Gemini, then the first house begins with 5 Gemini.
Q: What house system are you getting the orig. 5 Gem part?
A: We look it up from the sidereal time. The computer looks it up for you. We covered sidereal last week. Do you have questions on it? Quick review - solar time (what we use on our household clocks) is based on the rising and setting of the sun; sidereal time is based on the rising and setting of the stars. So we (or usually the computer) look up the ascendant based on the sidereal time for our chart. In this case I say it is 5 Gem.
The second house begins with 5 Cancer, the third house begins with 5 Leo and so on around the chart, with each house starting with 5 degrees of its respective sign. Again, it is pretty intuitive and doesn�t require extensive sines and tangents and arc-cosines and what not. The third system, Porphyry, introduces another player into the house calculations. This system finds the ascendant (Asc) and the Midheaven and divides the chart into quadrants. The first house begins with the degree of the ascendant, just like in equal sign houses. The 10th house begins with the Midheaven (MC, medium coeli). Each quadrant is divided precisely into thirds, marking the cusps of the intermediate houses. So let us say we still have an ascendant of 5 Gemini. Our midheaven is 20 Pisces. This gives us 2 signs and 15 degrees between the midheaven and the ascendant. We now divide that by 3, which gives us 25 degrees for each of those house cusps. Now we do the same calculation between the ascendant and the nadir (opposite the midheaven). The nadir marks the beginning of the 4th house, and in our example starts at 20 Virgo (exactly opposite from 20 Pisces). This gives us 3 signs and 15 degrees between the ascendant and the nadir. We divide this by 3, which gives us 1 sign and 5 degrees for each of those house cusps. So now our house cusps are 10th: 20 Pisces, 11th: 15 Aries, 12th: 10 Taurus, 1st: 5 Gemini, 2nd: 10 Cancer, 3rd: 15 Leo, 4th: 20 Virgo. What about the others? We simply extend our lines all the way across the chart, always landing at the degree of the sign exactly opposite. So 5th is the opposite of 11th and would be 15 Libra. The 6th is the opposite of the 12th and would be 10 Scorpio, and so on. Just remember that opposite house cusps are in the exact same degree of opposite signs.
My Q: So what would be the start of the 8th house?
Student�s A: 10 Capricorn same as 2nd house degrees but opposite sign
These are the only truly straight forward house systems, and I explain them to you just to help you get a feel for how a chart is constructed, and the relationships of the houses to the signs. The subsequent house system calculations involved far more trigonometry, and each was intended to improve the precision of astrologers� readings. But of course, that varies from person to person. Some prefer apple pie; some prefer pecan pie. Is one better than the other? Not necessarily. These house systems that we went over are based on degrees of longitude, which is of the zodiac. Later systems are based on degrees of right ascension or degrees of oblique ascension, or on degrees of heat in my oven.
Q: Latitude then would be the planets?
A: Latitude is how far they are from the centerline (horizontally) of the zodiac. The zodiac has an equator and latitude is the distance from that, just like on earth.
