Birth chart without a birth time: what holds, what falls

Often the time isn’t lost: it was written down when your birth was registered. Scotland records it for every birth, the United States puts it on the long-form certificate, and France has required it since 1803. England and Wales are the notable exception: their certificates show a time only for multiple births. So the right first step depends on where you were born.

Whatever the country, ask for the full record rather than the short version. A short certificate or abstract summarises the entry and may leave the time out; the long form reproduces it.

Where your time of birth is recorded, country by country

If the record doesn’t have it

That is the usual situation in England and Wales, and it also happens for births registered abroad. Three leads remain, from the most reliable to the most fragile.

• Hospital maternity records. They are not kept forever: in the NHS, maternity records are kept for 25 years after care has ended, and US rules vary from state to state. Beyond that, nothing guarantees they still exist, but asking only costs a letter.
• Family papers. Birth announcements, letters, a baby book: sometimes a time, often an approximation.
• Your parents’ memory. “In the morning”, “just after lunch”: not a time but a window. Write it down; it will come in handy later.

Check the time you have

A birth record gives the legal clock time of the day. Enter it exactly as written, with the place of birth: good software applies the history of daylight saving time by itself. Don’t convert it by hand, which is the commonest source of error. Britain has traps of its own: double summer time in the 1940s, and the British Standard Time experiment, when clocks stayed an hour ahead of GMT all year round, from 27 October 1968 to 31 October 1971. Be wary of round times such as 10:00 or 15:30: they may have been rounded.

Without a time, everything that depends on the Earth’s rotation disappears: the Ascendant, the Midheaven and the twelve houses turn through a full circle in twenty-four hours. Everything that depends on the planets’ own motion stays readable, because they move slowly: the Sun one degree a day, Pluto a few hundredths.

In the terms of the natal chart page: without a time you keep the actors (the planets), their styles (the signs) and their conversations (the aspects). You lose the stages they play on: the houses.

Element by element, what stays reliable without a birth time

Astrology is not an experimental science: all the more reason not to invent the data that is missing. An honest chart without a time says less, but it says nothing false.

Calculate your chart twice for your place of birth: once for 00:00 and once for 23:59 on the day you were born. Whatever is identical in both charts is readable. Whatever differs, a sign or an aspect, stays open. The test takes two minutes.

1. Enter your date and place of birth with the time 00:00. Note the sign of every planet.
2. Do it again with 23:59.
3. Compare line by line. Same sign: settled. Different sign: keep both possibilities.
4. Ignore the Ascendant, Midheaven and houses in both charts: they are bound to differ, and neither is yours.

If your family gave you a window, “in the morning” for instance, the test tightens: calculate the start and end of the window, 06:00 and 12:00, instead of the two midnights. The narrower the window, the more you can read.

To see how much the test matters, I ran it over sixty years of calendar: every day from 1 January 1950 to 31 December 2009, with the Swiss Ephemeris library. The figures barely move whether the days are counted in London, Paris, Madrid or New York time.

In other words, one person in two who doesn’t know their birth time cannot be sure of their Moon sign or of a personal planet’s sign. Leave the Moon out and the risk falls to 12.3% of days. The test tells you which half you are in.

To show the test on a case I didn’t choose, I drew a date between 1950 and 2005 and a French city at random: 25 February 1966, Clermont-Ferrand, time unknown. It is nobody’s chart in particular; it belongs to every child born in the area that day. Chance did its job well: it is a hard case.

The chart of 25 February 1966 at 00:00 and at 23:59

Positions calculated with Swiss Ephemeris, tropical zodiac, French legal time in 1966 (UTC+1, no daylight saving). Ascendant in Placidus houses for Clermont-Ferrand. ℞: retrograde.

Look at the last row: the Ascendant is in Scorpio at both midnights, after going round the whole zodiac in between. That is why the test rules it out from the start, even when both ends seem to agree.

Eight of the ten bodies stay in their sign. Two fall, and not just any two: the Moon moves from Aries into Taurus at 08:53, and Venus, which had just slipped back into Capricorn, re-enters Aquarius at 11:54. The day splits into three possible charts.

The Moon moves 12 to 15 degrees a day. If it stays in the same sign from the first to the last moment of your birthday, as it does on 56% of days, your Moon sign is certain. Only its degree floats, six to eight degrees either side of its noon position.

In that case you can read your Moon sign without reservation. Its aspects need more care: keep only those present at both midnights. A square with a 3° orb at noon may well not exist in the morning.

If it changes sign, you have two possible Moons. Read both portraits and ask yourself the question from the article on the Moon: what do you actually do in the ten minutes after something upsets you? The answer often points the way. Still, keep some reserve: we readily recognise ourselves a little everywhere, and a clue is not proof. If you know a time window, applying the two-midnights test to that window sometimes settles the question for you.

Without a time, two conventions dominate. The noon chart places the planets at their average position for the day: it limits the error on the Moon. The solar chart puts the Sun on the Ascendant and derives symbolic houses from it. Both are legitimate, as long as you never read them as a real chart.

The noon chart

It is the most widespread convention, and it is sensible for degrees. Its flaw lies elsewhere: it settles open questions without telling you. In the example, the noon chart shows the Moon at 1° 35′ Taurus and Venus at 0° 00′ Aquarius, having entered the sign six minutes earlier. It also shows an Ascendant at 19° Gemini, which is worthless.

Good practice fits in one sentence: degrees from noon, signs from the two-midnights test, and a mental line through the Ascendant and the houses.

The solar chart

Take the Sun’s degree as a notional Ascendant, then count twelve 30° houses from it. In the example, the Sun at 6° Pisces opens the first solar house: the Sun, Mercury, Mars and Saturn fall there, Jupiter in the fourth, Uranus and Pluto in the seventh, Neptune in the ninth, Venus in the eleventh under both hypotheses. Some prefer to cast the chart for sunrise, which comes to almost the same thing.

It is a finer version of the grid behind Sun-sign columns, which take your Sun sign as the first house. It is useful for following transits symbolically. It does not describe your life, since everyone born within a few days has the same solar houses. That is one of the reasons why your horoscope doesn’t sound like you.

Rectification reconstructs the time of birth from the person’s biography. You start from a window, even a wide one, and a list of events dated to the day: marriage, the birth of a child, a parent’s death, a move, an accident, a change of career. For each candidate time, you calculate the chart’s angles, the Ascendant and the Midheaven, the only points that move with the time, then check whether the events coincide with transits, progressions or directions to those angles. The window narrows as you eliminate the times that explain the fewest events, until you keep the one that explains the most with the fewest exceptions. The result is a working time, to be tested against new events, not a registered fact.

Seven steps, in order. The first two often make the other five unnecessary.

Send this list to the friend who “doesn’t know their time”: unless they were born in England or Wales, step 1 often settles it within days.