The Measurement of Houses
House cusps are imaginary "boundary lines" for the Houses, similar to the way Sign cusps are boundary lines for the Signs; but they differ in two ways.
Exceptions: There is a type of horoscope chart called "the Natural Horoscope" in which the Houses are assumed to start at zero degrees of a Sign and are all exactly 30 degrees in width, like the Signs. This is a "theoretical" chart used mainly for teaching the correspondence of Signs and Houses, but is very unlikely to occur in real life. In another kind of horoscope chart called a "Solar Chart", the Houses are assumed to be 30 degrees in width because the person's birth time is not known and the real House cusps cannot be determined.
Since positions in the horoscope chart are measured by degrees within the Signs, the House cusps do not always start at zero degrees of a Sign, but may start at any degree within a Sign.
- Since Houses are not always exactly 30 degrees in width like Signs, Houses may be narrower or wider than the Sign they overlap. However, Houses that are opposite each other in the horoscope chart will always be exactly the same width and start at the same degree of their respective opposite Sign.
Remember that the Sun and Moon and Planets appear in a Sign, and ALSO in a House. When the cusp of a House is within a certain Sign, that Sign is said to "rule" that House. Signs also appear to begin in a House, and may end in the same House or the next House. When a Sign begins and ends within the same House (which sometimes occurs when that House is wider than 30 degrees) that Sign is said to be "intercepted" in that House, since that Sign does not contain the cusp of any House and thus cannot "rule" any House.
To picture the overlap of Signs and Houses, imagine you are looking through two old wagon wheels set on the same axle, where one has 12 spokes perfectly spaced (the Signs) and the other has 12 spokes (the Houses) which are straight and run through the center, but are not spaced evenly around the circumference. (Actually, the Houses would appear evenly spaced at 30 degrees each if someone were born right on the Equator, but the further north or south of the Equator, the wider some Houses appear, which means others would appear narrower.)
Houses are always measured from
the Ascendant, which is a reference point based on the Earth's eastern horizon where the Sun appears to rise. Houses are areas in space which are, in effect, determined by the time it takes for the Earth to rotate on its own axis (the day/night or diurnal cycle). Thus each of the 12 Houses represents approximately one-twelfth of an Earth day of 24 hours (i.e. 2 hours), and we see the Sun appearing to move across the sky through six Houses in 12 hours (six 2-hour periods) from the eastern Horizon (the Ascendant) until it sets below the western Horizon (the Descendant).
The reality in which we live is called Space-Time or "Time and Space", and one cannot be separated from the other. You could say they "overlap". The Horoscope Chart and its Signs and Houses are representations of Time and Space, each representing both Time and Space in its own way. And Signs and Houses "overlap" in the horoscope chart.
Signs are areas in space which are, in effect, measured by the time it takes for the Earth to revolve around the Sun (the seasonal cycle). The Sun appears to travel across one Sign in one-twelfth of a year of 365.25 days. Each of the 12 Signs represents one-twelfth of an Earth year, or one month; and we see the Sun appear to move through one Sign in about 30 days, at the rate of one degree per day.
The House Cusps are imaginary lines in Space which are determined by mathematics. Just how their spacing is calculated depends on the system used to determine the House Cusps which fall between the Ascendant and Descendant (its opposite point) and between the Medium Coeli or M.C. (also called the Midheaven, which is the highest point in the sky where the Sun appears) and the Immum Coeli or I.C. (which is directly opposite the M.C.).
In nearly all House systems in use, the Ascendant is always the 1st House Cusp, the Descendant is the 7th House Cusp, the Midheaven is the 10th House Cusp, and the I.C. is the 4th House Cusp. It is the 2nd, 3rd, 5th, and 6th House Cusps which may vary among the systems used, and also the cusps which are directly opposite them - the 8th, 9th, 11th and 12th. For any system being used, the spacing of the House Cusps in a birth horoscope will also vary according to the latitude of the place of birth (its distance north or south of the Equator).
An exception is The Equal House System which is used when the birth time is not known; and therefore the true Ascendant Point cannot be calculated. In this case, 0 degrees of Aries is arbitrarily assigned as the Ascendant Point and cusp of the First House. All the Houses are assumed to be equal in width - 30 degrees each - and each House starts at 0 degrees of a Sign (which means the Houses One to Ten exactly overlap the Signs Aries to Pisces). In this simplistic House System, the Descendant Point will be 0 degrees of Libra, and the Midheaven Point will be at the start of the Tenth House, located at 0 degrees of Capricorn. Although this Equal House System is artificial and not based on the real birth time of the native, it can still reveal useful information and is better than not being able to cast a horoscope chart at all when the time of birth is unknown. It is also useful as a simple House System to start with when first learning about Signs and Houses.
A horoscope chart is composed of these two sets of sectors - Signs and Houses - which are superimposed upon each other (like two wagon wheels on the same axle), each representing a different kind of Time: months and days (the seasonal cycle), or hours and minutes (the diurnal cycle). In both cases, it is the Sun which marks the progress of Time. The Sun moves through 12 Houses in a day, and through 12 Signs in a year.
To understand the workings of the horoscope wheel, imagine a clock with 12 hour markings (the Houses) and minute markings (the Signs) - only there would be 12 "Sign" marks (not 60 "minute" marks) so the spacing of the two sets of markings would be roughly equal. There would be no moving "minute" hand, but a moving inner "Sign" circle with 12 Sign markings which moves clockwise on its own past the "House 1" mark at center left (where 9 would be on a clock) to indicate 2-hour periods (each Sign takes 2 hours to move up past that mark, which represents the eastern Horizon and the Ascendant point and 1st House cusp).
In this example, the Sun would be like a clock's hand, only it moves clockwise along with the moving inner face (within a Sign) as if that face were a second 365-day clock moving within the outer 24-hour clock face of 12 House marks.
And yet the Sun also slowly moves independently in a counter-clockwise direction along that inner Sign face like an hour hand on a clock, taking about a month to move past one Sign mark (the cusp of a Sign) and across that Sign to the next Sign mark, and taking 12 months to go all the way around the 12 Signs. It would take the Sign circle itself only 24 hours to move clockwise all around the wheel, taking the Sun with it; while the Sun was also slowly moving along its own course in the opposite direction.
It may help to avoid any confusion about the orientation of the standard horoscope chart if you remember that it represents a map of the heavens, i.e. a map of the sky from a viewpoint in the Northern Hemisphere on earth and looking up at the sky - not down from the sky (which is the way maps of the Earth are commonly oriented). Imagine you are lying on your back and facing south with your left arm extended to the east, as you look up at the sky. That is why East is to the left on the horoscope wheel, while East is usually to the right on a map of the Earth.
The horoscope chart represents your view facing south because you wouldn't see any of the zodiac signs or Planets if you were looking to the north. (If you lived in the Southern Hemisphere you would have to look north; but since the system of western Astrology we use was invented by peoples living in the Northern Hemisphere, its horoscope charts are based on that "from the north, looking south" point of view.)
In one day, the Sun appears to move clockwise around the horoscope chart because the Sun appears to move clockwise across the sky - if you are located in the Northern Hemisphere and looking south to see the Sun (because it never appears to the north). In one year, the Sun appears to slowly move counter-clockwise through the Signs in the horoscope chart because, from our viewpoint on Earth, over the course of a month it looks like the Sun is moving through the sky across one zodiac constellation (which is one of the particular star patterns which originally formed the Signs) to the next. Relative to the constellations (groups of stars), it moves counter-clockwise (from west to east, if you are looking from the Northern Hemisphere). At least it would appear that way if we could also see the stars behind the Sun while the Sun appears in the sky.
At night while the Sun is shining on the other side of the Earth, the Signs (and any Planets within them) appear to "rise" from the east and move clockwise from east to west in the sky during the night hours, as the Earth rotates once per 24 hours and faces all 12 constellations of the zodiac in sequence. (The zodiac is like a band in the sky through which the Sun and Moon and all the Planets appear to move, not appearing anywhere above or below that band of 12 particular constellations from which the names of the 12 Signs originated.)
You might say the Houses are "of the Earth", since the First and Seventh House cusps form the Horizon Line, and Houses are sort of "fixed" in a position bound to the Earth. You might say the Signs are "of the sky", since they are not fixed to the Earth, but appear to move across the sky; and they are marked by groups of stars in the sky.
Thus the horoscope represents BOTH the apparent motion of the Sun (our local star) and the Signs (distant star patterns) across the sky each day - and also its movement through the 12 Signs each year. The Sun (and one of the 30 degrees of whatever Sign it was in) would appear exactly on the eastern Horizon at the Ascendant point (the House 1 mark) exactly at sunrise, crossing from the first degree of the First House to the last degree of the Twelfth House. The Sun would appear exactly at the Midheaven point at the top of the wheel (the House 10 mark) exactly at noon.
Remember that in its diurnal (daily) motion, the Sun appears to move "backward" through the Houses - at the rate of about one degree every 4 minutes. The Signs also appear to move that way, along with the Sun and Moon and Planets. In its annual (yearly) motion, the Sun appears to move "forward" through the Signs - at a rate of about one degree per day. So if you had two horoscope charts cast for the same time of day, yet the second chart was for one day later, the Sun would appear at the same place in the same House, but in the later-dated chart it would appear one degree further along the Sign it was in at the time.
A horoscope chart would be like a "snapshot" of this odd clock face at any given instant in time. As with a man-made clock, you could tell the approximate time of day in that snapshot by noting where the Sun appeared (on the First House cusp at sunrise, on the Tenth House cusp at Noon, etc.) and you could also tell the approximate month of the year by noting what Sign the Sun was in. You could tell the approximate day of that month by noting the degree of the Sign at which the Sun was positioned. For each degree past zero, count one day past the date you see in those
Sun Sign "cusp date" tables - for example, if the Sun is at 10 degrees of the Sign of Capricorn, it is 10 days past December 22nd (the date when the Sun usually enters Capricorn at 0 degrees), and 10 days past that date would be January 1st.
It seems complicated at first to understand how to read a horoscope chart; but once you realize how the Signs and Houses actually represent areas in Space, and how they move over Time, you get a real appreciation for the ingenuity of the people who invented this system for showing a 4-dimensional image of Space-Time on a 2-dimensional piece of paper!
To understand how the Houses are calculated and constructed, you'll first need to know the important Points. Click for
Astrology FAQ 1. To understand what the Houses represent in terms of the human experience, click for
What Is the Meaning of the Astrological Houses.
Rising Sign Table |
Sun Sign Table.