Mean Motion. The average motion of any body within a given period. The mean motion of a planet is based on the
presumption that it moves in a circle at a uniform rate about the Sun. Actually the planets move in elliptical orbits, in
portions of which this motion is accelerated and retarded in ratio to their distance from the gravitational center. The
mean daily motions of the planets are:
...Pluto........0° 0' 14"........Jupiter........0° 4'59"
...Neptune......0° 0' 24"........Mars...........0° 31' 0"
...Uranus.......0° 0' 42"........Venus..........1° 36' 0"
...Saturn.......0° 2' 1"........Mercury........4° 6' 0"
...The Moon..(around the Earth)................13° 10'35"
...The Earth.(around the Sun)...................0° 59' 8"
The Heliocentric mean motions of the planets differ from their geocentric motions.
Mean Time. A consequence of the ellipticity of the Earth's track is that its orbital motion is faster near perihelion than
near aphelion. This has the effect of making the day longer in Winter than in Summer: not the day from sunrise to
sunset, but from one noon to the next. We keep our clocks from going haywire by the employment of the device
known as mean time, thereby measuring time not by the true Sun, as does the sundial, but by a fictitious mean Sun
which moves uniformly along the celestial equator, not along the ecliptic.
Measure of Time. Said of the method of calculating the time of an event from an Arc of Direction. The Ptolemy unit
is 1° of R.A. for each year of life. Later authorities divided the arc by the diurnal increment of R.A. made by the Sun
on the day of birth. Others employ a mean arc of 1° of RA., as the equivalent of the mean motion of the Sun, thus
adjusting the circle of 360 degrees to a year of 365¼ days. A method employed by Worsdale, Simmonite, Morrison
and others, consists of adding the Arc of Direction to the Sun's R.A. at birth, taking as years the number of days after
birth at which the Sun reaches this Advanced R.A. The method employed by Naibod (q.v.) is to determine the arc in R.
A., and consider each degree equal to 1 year, 5 days, 8 hours - a minute equal to 6 days, 4 hours. v. Directions.
Medical Astrology. That branch of Astrology which has to do with the planetary causes of disease.
Medium Coeli. v. Mid-Heaven.
Mediumship. The psychic, intuitive or telepathic faculty. Presumably attributed to the positions and aspects of
Neptune at birth.
Medusa's Head. Medusa, the mental and beautiful one of the three Gorgon sisters, who in one of Minerva's temples
became the mother by Neptune of Chrysador and Pegasus; therefore Minerva changed her hair into hissing serpents,
whereby everyone who looked at her was changed into stone. She was later decapitated by Perseus. It is represented by
Algol, in the constellation Persus. Its diameter is 1,060,000 miles, of the density of cork. To the Hebrews it was Lilith,
a nocturnal vampire - the serpent or "other woman" in the Garden of Eden.