Thursday, July 21, 2011

Mechanics of the Chart

The chart has a fixed inner  wheel divided into twelve parts, called houses, and an outer wheel (bottom figure) which rotates clockwise around the houses every 24 hours.

The outer revolving circle is the zodiac.

.   The twelve signs of the zodiac cross the ascendent every 24 hours

Every time we see the bowl of sky rotate once from east to west, we see the sun step one degree in the opposing direction.  (There are 360° in the zodiac; twelve signs of 30°each.)   In the northern hemisphere we see the ecliptic in the southern sky, so, unlike road maps, east is on the left and west on the right:  the sun rises on the left side of the horizon, ascends through houses 12-10 to the midheaven at noon, and sets on the right side of the chart (west) in the evening.

Think of all the planets as being attached to the outer wheel as it rotates around the inner wheel of houses.  

In the hand drawn chart above, 4°45’ is coming up on the eastern horizon and the sun is at 25°58’ in the 8th house.  If I had made the post 4 hours later, the sun would have been about to set (followed by Neptune, the moon and venus). When I did publish the post at 1:44pm, Pluto was setting.  

Pluto has been in Capricorn since 2009 and will not cross into Aquarius until 2023; it's a very distant object that takes a long time to orbit the sun.

A 5:44 publishing time would have put 24°43’ rising, and mars, instead of being in the first house, would have been above the horizon in the last house.


In the four hours after I published my first post, Mars rose, Mercury set, the Sun advanced to two minutes behind Neptune, and the Moon went from 3°Pisces 09’ to 5°Pisces 07’ and overtook Venus.

Why Planets go through the Last House First

You might wonder why Sun and the other planets go backwards through the houses; in other words why is the 12th house the first place we see the Sun when it rises?  Shouldn’t it be called the first house?

Actually houses are a relatively modern addition to astrology charts.  Originally the planets were spaced out around a square page more or less in a circle with their zodiac signs and sometimes the degree of the sign indicated.  Houses come from the Greek ‘topoi’ which in old manuscripts could mean a couple of things.

In one usage, a planet was ‘located’ a certain number of signs from another planet, for instance the Sun in Aquarius is the 7th sign from Mars in Leo.  This is usually translated as the Sun being in Mar’s 7th mansion or 7th house.  The second way ‘topoi’ is seen used is where we get the modern concept of houses;  locating a planet a certain number of signs from the ascendant.  In the Birth of a Blog chart the Aquarian Sun is in the 8th sign from the Cancer Ascendent  (counting Cancer as the first).  Another way to think of it is that Aquarius will be the 8th sign to rise after Cancer.   We went from a sign being located 8th in line to ascend, in manuscripts before the Renaissance, to a sign covering the 8th house in the modern chart.

If you find this difficult to understand you are not alone.  All you have to do is go to the Astrodienst  Extended Chart Selection area for picking the kind of house division system you want to use- the 15 choices listed will give you an idea of just how unsettled the modern concept of houses is. 

The thing to remember is that houses indicate the order in which things appear above the ascendant.   As soon as a planet or sign rises it goes to the back of the line and must follow the rest of the wheel around before it can show itself again on the eastern horizon. 

For more on houses with a couple of example charts go to Houses