Science / Astrology / Precession: The circular motion of Earth's axis around the pole of the ecliptic, caused by the gravitational pull of the Sun and Moon on the bulging part of the equator. One complete revolution takes approximately twenty-five thousand years to complete.

Precession Of The Equinoxes

Science / Astrology / Precession Of The Equinoxes: The gradual westward shift (about 50' each year) of the equinoctial points along the ecliptic due to the ecliptic due to the rotational movement of the poles of Earth's axis. This phenomena creates an MORE

Sidereal Day

Science / Astrology / Sidereal Day: Twenty-four sidereal hours equal to 23 hours, 56 minutes and 4 seconds of clock time. MORE

Sidereal Time

Science / Astrology / Sidereal Time: Time measured in relation to fixed stars, as distinguished from clock time, based upon the Sun's position relative to Earth. Astrological time data is listed in sidereal time units. MORE

Tropical Zodiac

Science / Astrology / Tropical Zodiac: The circle of signs that follows the apparent path of the Sun (ecliptic). Also called the movable zodiac because it shifts slightly each year relative to the constellations of the sidereal zodiac. See MORE

Ptolemy, Claudius

Science / Astrology / Ptolemy, Claudius: A great astrologer, astronomer and geographer of the second century (ca. 100-178 A.D.) who developed the theory that Earth is the motionless center of the universe about which the planets, sun and Moo MORE

Great Year

Science / Astrology / Great Year: The astrological year based on the time it takes Earth's axis to complete on revolution around the pole of the ecliptic, about twenty-five thousand years. A Great Year is divided into twelve 'months' MORE