Step one
Resolve the birth instant
A birth chart starts with a real moment. The selected city supplies latitude, longitude, and an IANA timezone; your local date and time are then resolved against historical timezone rules.
This matters around daylight-saving changes. A wall-clock time can be repeated or skipped, so ChartOdyssey rejects ambiguous or nonexistent times instead of quietly choosing an instant for you.
Step two
Calculate four placements
The Sun, Moon, and Venus come from geocentric planetary positions. Rising is calculated from the eastern horizon, so it also depends on the exact time and coordinates.
- Sun: the central, outward color role.
- Moon: the private and emotional color role.
- Rising: the first-impression color role.
- Venus: the attraction and aesthetic color role.
Honest uncertainty
Unknown time changes the result
Without an accurate birth time, Rising remains unavailable. The Moon is checked across the local day; if it changed signs, the result is marked as a boundary-day estimate rather than presented as exact.
Step three
Map placements to an original color system
Each of the 12 signs has a distinct base color for each of the four placement roles, producing 48 original definitions. The mapping is editorial and interpretive; it is separate from the astronomical calculation.
Classic preserves the base color. Soft raises lightness and tempers saturation. Deep lowers lightness while keeping the palette recognizable.
Data boundary
Keep private inputs out of the output
Calculation and PNG rendering happen in your browser. The share URL contains only the resulting signs, not your date, time, city, timezone, or coordinates.