⌖ Chart accuracy and uncertainty

Birth data comes first

A precise-looking chart cannot repair an uncertain input. Confirm the calendar date, local clock time, birthplace, and the source of the record. A rounded time such as noon may be a placeholder rather than a measured birth time.

Timezones are historical

A modern timezone offset is not always the offset that applied on a birth date. Daylight saving rules and regional boundaries change. Converting local time to UTC requires the historical rule, not simply subtracting today’s offset.

Match the reference frame

Compare tropical with tropical, and a named sidereal ayanamsha with the same ayanamsha. Also check geocentric versus topocentric and apparent versus geometric positions. Small differences near a sign or house boundary can change a label.

Choose honest precision

Seconds or many decimal places in the output do not imply equivalent certainty in the input. When a birth time is unknown, calculate a range across the day if needed. State whether the Moon could change sign and avoid presenting houses or angles as established facts.

Understand the tool’s scope

Astrology.mobi’s planet explorer calculates tropical geocentric positions for a chosen UTC moment. It converts a user-supplied local time and UTC offset, but does not look up historical timezone rules, infer birthplace, or calculate an Ascendant or houses. Its wheel is a zodiac-position diagram, not a complete location-based natal chart.

Compare with a second calculation

For an important boundary case, verify the timestamp and settings against another reputable ephemeris. A disagreement should trigger inspection of inputs and conventions before interpretation. Symbolic confidence is not a substitute for checking the calculation.

Explore the sources

• Astronomy Engine: calculations and source