How birth time affects your chart

Some parts of a chart barely change over a day; others change every few minutes. Knowing which is which helps you judge how much weight to give a reading.

What changes quickly

• The ascendant moves through all twelve signs in about 24 hours — roughly one sign every two hours, faster or slower depending on the sign and your latitude.
• Because houses are counted from the ascendant, every house placement depends on it. So do Lal Kitab placements, which use the houses.
• Divisional charts such as the navamsa ascendant can change within minutes.

What changes slowly

• The Moon moves about 12–15° a day, so it changes sign every two to two-and-a-half days and nakshatra roughly once a day.
• The Sun moves about 1° a day; the other planets move more slowly still.

Time zones are part of the birth time

A birth time is only meaningful together with the clock rules in force at the time. India used a different offset during the Second World War, and many countries observe daylight saving. Astroilaz resolves the time zone from the birthplace's coordinates and the IANA time-zone database, which records these historical changes. If a time fell in a daylight-saving gap or overlap, we ask you to confirm rather than guessing.

If you don't know your time

Astroilaz will not invent an ascendant. Without a birth time we calculate the planets for local noon, show planet signs and other time-independent information, and use the Moon sign as a reference point (Chandra lagna). If the Moon changed nakshatra on your birth date, we say the dasha sequence can't be determined.

If you know an approximate time, tell us how far off it could be. We'll flag any element — such as the rising sign — that could change within that window.