Guide
Calculate the Sun, Moon and planet positions for a UTC birth date and time. Get a tropical zodiac wheel and downloadable planetary chart, without invented houses.
Convert the recorded time before calculating
Use the birth date and clock time from your source, then determine the UTC offset that applied in that place on that date. Daylight saving rules may differ from current rules. Subtract a positive offset and add a negative offset; 02:00 at UTC+03:00 becomes 23:00 UTC on the previous day. Enter the converted date as well as the converted time. This tool deliberately requires UTC rather than silently guessing a timezone.
Read the wheel and longitude table together
The zodiac here is tropical: twelve equal 30-degree sectors measured from the equinox. It does not use the irregular boundaries of astronomical constellations or a sidereal offset. The small marks around the inner ring show calculated longitudes, while abbreviated labels are staggered for readability. Use the table for the exact displayed values. R identifies negative apparent longitude motion over the centered one-day sample.
Keep unknown time separate from calculated precision
A software calculation can produce a precise number for a guessed time, but that does not make the birth time known. If the time is unknown, mark it approximate and treat noon UTC as a placeholder. Recalculate at the start and end of the plausible interval to see whether a sign changes. This is especially useful for the Moon. Rising signs and houses require additional location and time calculations and are not included here.
How the result is made
Astronomy Engine 2.1.19 computes light-time and aberration-corrected geocentric vectors for the Sun, Moon, Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. Ecliptic converts those vectors to the true ecliptic and equinox of date. Each 30-degree tropical zodiac sector names a sign. A centered one-day longitude difference estimates direct or retrograde motion. Display rounds to 0.01 degrees; rounding is not a claim about birth-time certainty. No latitude, longitude, ascendant, houses or predictive reading is calculated.