Start from a life date
Secondary progressions use the symbolic rule that one day after birth in an ephemeris corresponds to one year of life. This tool takes a recorded birth instant and a chosen later UTC target instant. It divides elapsed life days by 365.24219, treating that quotient as symbolic days after birth. The result is a target point in the ephemeris, usually only a few weeks after the original birth even when the real target is decades later.
From that symbolic ephemeris point, the calculator finds the preceding exact New Moon. It searches for a zero-degree geocentric ecliptic Moon–Sun longitude difference. The red inner ring plots ten actual planetary longitudes at that found symbolic instant. The blue outer ring plots ten planets at the recorded birth instant. The two rings are not duplicate drawings, and the red ring is not the current sky on the chosen life date.
There are three distinct timestamps
The birth UTC instant anchors the whole calculation. The target UTC instant is the life date the visitor wants to examine. The New Moon’s symbolic UTC instant is the actual astronomical conjunction found in the ephemeris near the progressed point. That conjunction is also mapped back into a corresponding life date: each symbolic day from birth is multiplied by 365.24219 real days. The tool labels all these clocks rather than placing the mapped life date on the red ring as if it were an astronomical observation.
If a New Moon occurs 30 ephemeris days after the birth instant, this method maps it to age 30 years. The exact 365.24219-day year key refines the resulting UTC life date. If the previous New Moon falls 10 ephemeris days after birth and the target corresponds to day 20, that day-10 New Moon remains the last progressed New Moon for the target. The next one may map to years later.
Why a prior event can map before birth
A target immediately after birth can fall before the first subsequent New Moon in the symbolic ephemeris. In that case the immediately previous phase is a real New Moon before birth, and its mapped life age is negative. The tool reports that date honestly. A later target will eventually select the next symbolic phase after birth. This boundary is a feature of searching previous phases, not a chart error or an implied prenatal event at the life date.
What the wheel and table mean
The blue outer ticks and glyphs are natal bodies. The red inner ticks and glyphs are bodies at the symbolic New Moon. The zodiac starts at 0° Aries at the top and advances clockwise. Central division lines are natal house cusps. The red radial line marks the event Sun–Moon longitude, where the red luminaries coincide. Planet symbols can overlap at a conjunction, so the exact degrees in the comparison table should be used for close reading.
The birth place determines natal angles and houses. This implementation leaves the progressed ring without its own angles and houses because secondary progression techniques have multiple methods for advancing angles and cusps. Applying birth houses to the red bodies would quietly conflate two different charts. The output therefore supplies a house only for the birth position of each planet. Choosing another birth location changes those local houses, not the geocentric New Moon instant.
Numerical choices and interpretation limits
The event search and event ring both use geocentric ecliptic positions without aberration. The birth ring uses the site’s apparent geocentric chart engine; it labels that convention beside the wheel. The difference is small but relevant to claims of exact orb. The phase search residual is reported in degrees to show that the red Sun and Moon really meet at the returned instant. Different ephemerides, progression keys, or event inclusion rules may give slightly different dates and displayed degrees.
Astrologers sometimes read a progressed New Moon as the start of a symbolic cycle. The calculator itself verifies only the phase geometry and the chosen time mapping. It cannot establish that an event will occur on the mapped date. If the birth hour or historical UTC offset is wrong, even a small symbolic shift can become a noticeable shift on the life calendar. Use a documented birth time for precise mapping; otherwise treat the date as exploratory.
The progressed lunation calendar also shows previous and next Full Moons. A progressed Full Moon is 180° separation in the symbolic ephemeris, so it has a different date from this New Moon comparison. To see the independently calculated red and blue rings, draw the progressed New Moon chart.