The Charts · Inside the birth chart
Same birthday, same sun sign, different rising sign. The clock decides.
What is a rising sign, and why does it need a birth time?
Your rising sign, or Ascendant, is the zodiac sign that was coming up over the eastern horizon at the minute and place you were born. The whole zodiac rises once a day, so the rising sign changes about every two hours. It needs your birth time and birthplace, and it sets the houses of the chart.
On your card: pages 1, 3, 4 and 5 Your rising sign, Ascendant, Midheaven and houses, The people in your life, Your work, Your money
What it is
As the Earth turns, the zodiac wheels across the sky like everything else: each sign rises in the east, crosses the southern sky and sets in the west. At any moment one degree of the zodiac sits exactly on the eastern horizon. That degree is the Ascendant, and the sign it falls in is your rising sign.
Put astronomically, the Ascendant is where the horizon crosses the ecliptic in the east, and the Midheaven is where the meridian, the north–south line through the point overhead, crosses it. Opposite them sit the Descendant, setting in the west, and the IC, under your feet. Together they are the four angles. 1
The Greeks built the whole art around this point. They called it the horoskopos, the hour-watcher, and horoscope comes from it. Babylonian horoscopes never recorded it; Greek ones listed it beside the Sun, Moon and planets. 2
Tradition reads the rising sign as the way a person meets the world: manner, first impression, the face at the door. The sun sign is the deeper current underneath. That is the general idea, the same for everyone with that rising sign.
How it is calculated
- Look up the place. The machine finds your birthplace's latitude, longitude and time zone, with the daylight-saving rules that applied on your birth date.
- Turn clock time into star time. The birth time becomes Universal Time, then local sidereal time: how far the sky had turned, as seen from your longitude, at that minute.
- Find the rising degree. From the sidereal time and your latitude, spherical trigonometry gives the degree of the ecliptic on the eastern horizon. The same sum gives the Midheaven.
- Count the houses. With whole-sign houses, the rising sign is the 1st house and each sign after it is the next house, round to the 12th. The sign opposite, holding the Descendant, is the 7th.
Why the minute and the place matter
Twelve signs rise in about 24 hours, so each takes about two hours on average, but not evenly. Away from the equator some signs climb steeply and rise in under an hour while others lie low and take three hours or more. In the Northern Hemisphere, Capricorn through Gemini rise quickly and Cancer through Sagittarius slowly; south of the equator it is the other way round.
Near a sign boundary, ten minutes can change the answer. That is why the machine prints no rising sign at all without a birth time rather than one that might be wrong.
The place counts as much as the time. At the same instant Chicago and Paris have different signs rising, because they face different parts of the sky. A wrong time zone or a forgotten daylight-saving hour shifts the whole chart by an hour, which is about half a sign.
Ptolemy knew the problem. Only an astrolabe could give the minute of birth, he wrote; sundials shift and water clocks clog. Most births in history were timed by neither. 3
The houses start here
Because the houses are counted from the rising sign, the rising sign is what turns a list of planets into a map of a life. In the traditional scheme the 1st house is the self, the 2nd possessions and earnings, the 7th partners, the 10th career and public standing, and the rest cover family, children, friends, travel and what lies hidden.
The card reads its people, work and money sections from these houses when it has your birth time and place, and falls back on planets alone when it doesn't. More on house systems on the birth chart page. Houses, and why the machine uses whole signs →
Where the rising sign comes from
Era by era, with sources. More in the Reading Room.
- Babylon410–69 BCEBabylonian horoscopes give the signs of the Sun, Moon and planets but no rising point. Their positions come largely from the temple's records of observation. 2
- Hellenistic1st century BCEGreek horoscopes add the horoskopos, the part of the zodiac rising at the moment of birth, and work everything out from tables instead of the sky. 2
- HellenisticHellenistic eraThe houses are counted from the rising sign, one whole sign per house: the system the historian James Holden identified as Hellenistic astrology's own. 1
- Roman Egypt2nd century CEPtolemy writes a chapter on finding the degree of the horoscopic point, admits most birth times are rough, and gives a method for correcting them. 3
- Medieval Englandc. 1390sChaucer's Wife of Bath explains her temperament by her chart: Venus and Mars at her birth, Taurus rising with Mars in it. 4
- England1647William Lilly's Christian Astrology teaches readers to set up a chart for themselves from an ephemeris, angles and houses included. 5
- Modern1971Tables for Koch houses are published, one of the newest quadrant systems. Placidus remains the most widely used, perhaps because of the tables printed in Raphael's Ephemeris. 1
- Computers1972 onwardComputer chart services such as Neil Michelsen's Astro Computing Services do the spherical trigonometry in seconds. Getting a rising sign stops being an afternoon's arithmetic. 6
Asked at the booth
Can I know my rising sign without a birth time?
Not reliably. Every sign rises at some point on every day of the year, so the date alone fits all twelve. A rough time (morning, afternoon) narrows it to a few candidates; only the actual time settles it.
Is the rising sign the same as the Ascendant?
Nearly. The Ascendant is the exact degree on the eastern horizon; the rising sign is the sign that degree falls in. "My Ascendant is 12° Libra" and "I'm a Libra rising" describe the same thing at two levels of detail.
Does daylight saving time matter?
Yes. A clock running an hour ahead puts the sky an hour off, about half a sign of rising. The machine applies the time zone and daylight-saving rules that were in force at your birthplace on your birth date.
What is the Midheaven?
The degree of the zodiac crossing the meridian, the highest point of the ecliptic in the sky at your birth. Tradition ties it to career and reputation. Like the Ascendant, it needs the time and place.
Why did my rising sign change when I corrected my birth time?
Because the rising sign moves fast, about one sign every two hours and faster for some signs. A correction of even a quarter of an hour can move the Ascendant across a sign boundary, and every house moves with it.
Go deeper
That's how it works for everyone. Your card works it out for you.
This page explains the method and where it comes from. What it says about you is sealed on your card, worked out from the day, the minute and the place you were born.
What your card covers
See all six pages, sealedFold the pages back
1 Who you are
2 The machine says
3 Your sky
4 Love & your people
5 Work & money
6 Your year ahead
Sources
- The Astronomy of Houses, The Urania Trust (Graham Bates, 2013–2014; posted 13 June 2016). Read on .
- Alexander Jones, The Horoscope Casters (Archaeology Odyssey 3.6, 2000), New York University Faculty Digital Archive. Read on .
- Ptolemy, Tetrabiblos, Book III, chapters 1–9 (chapter 2: Of the Degree of the Horoscopic Point), LacusCurtius, University of Chicago (Loeb Classical Library translation by F. E. Robbins, 1940). Read on .
- The Wife of Bath's Prologue and Tale (interlinear translation), Harvard University, Geoffrey Chaucer Website. Read on .
- William Lilly, Christian Astrology: Modestly Treated of in Three Books (London, 1647), Wellcome Collection (electronic reproduction of the Library of Congress copy, Early English Books Online). Read on .
- Neil Michelsen (1931–1990), The Urania Trust, 28 February 2016. Read on .