Knowing Your Birth Time And Location Or Not

When computing an astrological birth chart, one may or may not know their birth time and birth location. If this information is available, then, one's ascending sign and moon position can be computed accurately.

Ascendant (or Rising Sign)

The ascendant is the eastern rising zodiac sign at the birth location, at birth time. Since the earth takes 24 hours to rotate on itself and since there are 12 zodiac signs, the rising sign changes about every two hours. Hence, you need the birth time and birth location to compute one's ascendant. 10 AM in Paris is not 10 AM in Delhi.

If one cannot compute the Ascendant's position, one cannot compute the Imum Coeli, Descendant and Midheaven positions.


The moon rotates around the earth in 28 days. Therefore, it moves about 12.8° (=360°/28) in the sky per day, which is nearly half the size of a house (30°). If one does not know their birth time and birth place, it is not possible to compute the position of the moon accurately. This means that aspects involving the moon cannot be computed accurately too. Orbs are usually at most 10° wide.

Since other astral items move much more slowly in the sky, not knowing one's birth time and location is not a real issue. The lack of accuracy is too small to worry about it.