The Sunward field guide
How birth time affects an astrocartography map
Birth time matters because the map depends on a specific instant and the Earth’s orientation at that instant. A small clock-time change can move a line and reorder cities; an unknown time cannot support a precise personal map.
Can I use astrocartography without a birth time?
You can learn how a map works with a clearly labelled example, but an unknown birth time does not support a precise personal map in Sunward Atlas. Each supported line combines a planet with an angle, such as Venus DSC. Its position depends on the birth instant. Choosing “I don’t know the time” stops the calculation. An example or earlier result may remain visible; it is not a new calculation for an unknown time.
A noon chart is a chart for noon, not an estimate recovered from missing information. Do not replace an unknown time with 12:00 and then treat its lines or city distances as your personal result. Reading a general natal chart without a birth time is a different task from locating angular lines on Earth.
A different time produces a different map
Astrocartography places celestial positions on the rotating Earth. When the birth time changes, the relationship between the sky and geographical longitude changes too. A line that passes close to a city for one input can pass farther away for another. The effect depends on the line, the location, and the size of the time change.
There is no single minute threshold that guarantees a map is “accurate enough” for every use. A broadly remembered part of the day, a rounded clock time, and a recorded time should carry different levels of confidence. Calculation can show the sensitivity to those inputs, but it cannot establish which remembered input is true.
A worked example: change only the clock time
Start with the synthetic input 1995-06-15 at 09:30 in Asia/Shanghai. Keep the same date and Shanghai time zone while changing the clock time to 09:40, then 10:30. The table uses the same calculation engine and the same Los Angeles coordinate throughout. These are controlled teaching calculations, not observations of anyone's life.
At 09:30, Los Angeles is about 77 km from Venus DSC. At 09:40, its distance is about 131 km; at 10:30, it is about 1,133 km. Changing the input changes a geometric result. It does not measure how a person's relationships change.
| Local time | Resolved UTC | Sun MC longitude | Los Angeles to Venus DSC |
|---|---|---|---|
| 09:30 | 1995-06-15 01:30 UTC | 157.57° E | 77 km |
| 09:40 | 1995-06-15 01:40 UTC | 155.07° E | 131 km |
| 10:30 | 1995-06-15 02:30 UTC | 142.57° E | 1,133 km |
Enter the local time, then check the time zone
Enter the local clock time recorded for the birthplace, rather than converting it yourself before entering it. For the initial example, 09:30 in Asia/Shanghai resolves to 1995-06-15 01:30 UTC. Sunward Atlas uses the selected city's named time zone to make that conversion.
Historical daylight-saving rules matter. On some transition dates, a local clock time never occurred; on others, it occurred twice. The current calculator rejects both situations rather than choosing an instant silently. If you encounter that message, check the birth record and historical context. The interface currently does not provide a control for selecting between two repeated clock times.
Time-zone rules come from the browser or runtime database. A successful calculation confirms that the software resolved the input, not that every historical jurisdictional detail has been independently checked. Keep the displayed local time, time zone, and UTC together when comparing results.
What to do if the time is uncertain or unknown
Start by establishing what your source actually tells you. A recorded minute, a rounded recollection and a completely unknown time need different next steps. Keep the source and its uncertainty alongside any calculation.
If you have a genuinely bounded range, manually calculate plausible times within it and keep separate downloaded HTML reports. Change only the time so the comparison is interpretable. Checking two endpoints gives two samples, not a guarantee that you have captured every variation between them. The tool does not automate a range comparison or rectify a birth time from life events.
| What you have | What to do next | What the result can establish |
|---|---|---|
| A recorded time | Keep the record, local clock time and birthplace together; check the displayed time zone and UTC. | A calculation for that input, not proof that the record itself is exact. |
| A remembered or rounded time with a credible range | Keep the uncertainty visible; manually calculate plausible times and save separate HTML reports. | Sensitivity at the sampled times, not the true time or every result within the range. |
| No usable time or range | Look for a birth record or another reliable source; use the labelled teaching example to learn the interface. | How to read a map, not your personal line locations. |
Compare the same quantity each time
When reviewing different calculations, compare the same city and the same line before comparing the shortlist order. A theme can select a different nearest line for a city, and the city may leave the displayed shortlist. A change in rank alone hides those details.
Also keep the calculation method fixed. Geometric and refracted horizons, geocentric and topocentric positions, and different historical time-zone resolutions can produce differences between tools. Matching one screenshot is not proof that all the underlying assumptions match. The methodology page states this calculator’s choices so a comparison can begin with those assumptions.
Sources and calculation notes
Technical references below explain the calculations. Practitioner references, where included, document the interpretations attributed to them in the text. Neither type establishes that a planetary line predicts a life outcome. How we use sources