How to calculate a natal chart
Three parameters are needed for the calculation: date, time, and place of birth. The date determines slow-moving planet positions. Time determines the Ascendant and house system — without it, the chart is incomplete. The location is needed for UTC conversion.
What a natal chart shows
Sun — core identity and life direction. Moon — emotions and the unconscious. Ascendant — how others perceive you. Mercury — thinking. Venus — love and values. Mars — action and motivation.
Houses show where a planet's energy manifests: 1st house — personality, 7th — partnership, 10th — career. Aspects are connections between planets: harmonious (trine, sextile) and tense (square, opposition).
Why calculation accuracy matters
A 1° error for the Moon equals a 2-hour shift. For the Ascendant, it can mean a sign change. Free online calculators often use simplified formulas that produce errors of several degrees. We use Swiss Ephemeris — the same engine found in professional software by Astrodienst, Solar Fire, and Sirius. Data comes directly from NASA JPL planetary ephemerides — the very same ones used to calculate spacecraft trajectories.