Every house system is also affiliated with a zodiac sign can be dependent on the rotational movement of Earth on its axis, but there is a wide range of approaches to calculating house divisions and different opinions among astrologers over which house system is most accurate. To calculate the houses, it is necessary to know the exact time, date, and location. In natal astrology, some astrologers will use a birth time set for noon or sunrise if the actual time of birth is unknown. An accurate interpretation of such a chart, however, cannot be expected.