Why an accurate birth time changes a chart
The Ascendant and house cusps rotate quickly. This is what an uncertain birth time does to a reading.
Bibliothèque éditoriale — ces articles de référence sont rédigés en anglais.
What moves fast and what does not
The Sun changes zodiac sign roughly monthly, so a birthday alone fixes the Sun sign. The Moon moves about a degree every two hours. The Ascendant and house cusps, however, depend on the Earth's rotation and can shift noticeably within a couple of hours.
Consequences of an unknown time
- The rising sign may be indeterminate.
- House placements cannot be fixed reliably.
- Moon-related placements may be approximate.
- Angle contacts in synastry become less certain.
The honest response
A tool should say which parts are estimates rather than filling the gaps with invented precision. NaYinTop marks approximate placements as such, and still lets you explore the parts of a chart that do not depend on an exact clock time. All of this is for entertainment and self-reflection only.