Unknown birth time: what happens to your birth chart?

Why your birth time matters so much

The Ascendant, or rising sign, is the sign that was rising on the eastern horizon at the minute you were born. As the Earth turns, it moves about one degree every four minutes and changes sign roughly every two hours on average: faster for Pisces or Aries, more slowly for Virgo or Libra at mid-northern latitudes. Half an hour can be enough to tip it over, which is why the rising sign calculator asks for the time to the minute.

The twelve astrological houses follow from it. They start from the Ascendant and the Midheaven, and show the area of life where each planet acts: relationships, work, home, money… Without the time, you know your Venus is in Libra, but not whether it plays out in the house of partnership or in the house of career.

The Moon is the fastest body in the chart: it moves twelve to fifteen degrees a day and stays a little over two days in each sign. On more than four days out of ten, it changes sign during the day. Two people born on the same date, one in the morning and one in the evening, can therefore have different Moon signs.

How to find your birth time

Your birth time is almost always written down somewhere: you just need to know where to look. Start with official records, then move on to family papers.

• In the UK: in England and Wales, the birth certificate usually shows the time only for twins and other multiple births; in Scotland, it appears on the certificate. Hospital records or the baby’s red book may also note it.
• In the US: the long-form birth certificate, from the vital records office of the state where you were born, often shows the time; short versions may leave it out.
• In France and elsewhere: in France, the full copy of the birth record (copie intégrale), free from the town hall of the place of birth, shows the time. Elsewhere, ask the civil registry for the full version of the record, as short certificates do not always include it.
• Family: your parents, a birth announcement, a baby book, a letter from the time. An approximate time (“late morning”) already helps, but it remains an estimate.

Enter the time exactly as written, in local time: that is what the form asks for. The site applies the daylight saving time or standard time in force that day on its own, so do not adjust it by hand. How this works is explained in how accurate the calculation is.

Birth chart without birth time: what the site does

In the free birth chart form, tick “I don’t know it” next to “Time of birth”. The hour lists disappear and a note sums up the rule: without a time, the chart is computed for noon, the signs are correct, but the Ascendant and the houses are not shown. The rest of the form stays the same, as the step-by-step guide shows.

The result page follows the same logic: anything that depends on the time is left out rather than guessed. Here is what you see.

• At the top of the page, the birth line reads “(time unknown)”, and the Ascendant box shows “Birth time required”.
• The wheel shows your planets in their signs, without houses or Ascendant: its caption reads “no houses (time unknown)”.
• “Your chart in detail” keeps the interpretation of each planet in its sign and all the aspects; the house texts and the Midheaven do not appear.
• The express reading is composed without the Ascendant, the houses or the Midheaven, and talks about your Moon without dwelling on its sign.

What stays reliable without the time

Most of the chart holds without the time. The Sun moves one degree a day, Mercury, Venus and Mars about two degrees at most, the slow planets far less: calculated for noon, they land in the right sign unless one of them changes sign that very day. The aspects between planets and the retrogrades stay correct, and the dominant elements and modes are worked out from your planets.

Two placements deserve a closer look, and the page gives you what you need to decide: the degree of your Sun and of your Moon is shown at the top, in their boxes. Use it like this:

• Moon between 9° and 21° of its sign: it was there all day long, so your Moon sign is certain.
• Moon between 0° and 8°, or between 22° and 29°: depending on your time, it may have been in the next or previous sign. Read both, keeping in mind that only the time can settle it.
• Sun at 0° or 29°: you were born on a day when the Sun was changing sign. The sign shown is likely, but the time can tip it over.

Aspects to the Moon are the only ones to read with caution: in twelve hours it covers six to seven and a half degrees, enough for a tight aspect to appear or vanish.

What needs the exact time

The other free tools also work without the time, with the same rule. My transits reads the sky’s passages over your planets and offers “Add my birth time” so your houses are read too. The compatibility chart shows “time unknown” in place of the missing Ascendant, and the solar return warns that the year’s rising sign is indicative, since the moment of the return can shift by a few hours.

The written reading, on the other hand, needs the exact time: it is required when you order, because it sets the Ascendant and the houses, a large part of the reading. Even if your chart was calculated without a time, the hour lists stay empty in the order form until you choose one. To give a reading to someone whose birth time you do not know, the gift voucher lets them enter their own birth details.

With My Birth Chart+, the tailored horoscope follows your planets without the Ascendant or the houses while the time is missing, and the tailored reading in PDF also requires the exact time.

Adding the time later

Once you have the time, simply calculate your chart again with it: the wheel gains its Ascendant, its Midheaven and its twelve houses, and each planet takes its place in an area of life. You can keep that chart in your free space, then learn to read your wheel house by house.

A rounded time (“around 3 pm”) can be put to the test: calculate the chart for 14:30, then for 15:30, since the form uses the 24-hour clock. If the Ascendant stays in the same sign, you can rely on it; if it changes, keep both in mind until you find the exact time.