Z

Zenith. Mathematically, the Pole of the Horizon. The point directly overhead, through which
pass the Prime Vertical (q.v.) and Meridian circles. Every place has its own zenith, and the
nearer a planet is to that zenith, the more powerful is its influence.. The term is sometimes
loosely applied to the cusp of the Tenth House, which strictly speaking is only the point of the
zodiac or ecliptic through which the meridian circle passes. v. Celestial Sphere.

Zero Hour Circles. The Secondary Hour Circles drawn through the celestial poles and
perpendicular to the celestial equator are termed Hour Circles, while those drawn parallel to the
celestial equator are called parallels of declination. The angle at the pole which this circle makes
with the meridian through any other place is called longitude.

The Hour Circle passing through the point of the Spring Equinox is known as the Zero Hour
Circle. At the time the Great Pyramid was built, the Zero Hour Circle cut the Earth at that point,
just as some centuries later it cut the location fot eh Greenwich Observatory when that was
constructed. The world time should follow the precession of the Equinoxes, but this would entail
not only the relocation of the Observatory every 70 or 700 years but of all the time zone
meridians - obviously a difficulty not easily overcome. To obviate that, world time has been
made synonymous with Greenwich Standard Time. However, the measurement in degrees of
Right Ascension of points along the Ecliptic, beginning at the point of the Spring Equinox, must
of necessity be correct, and while the required adjustment is but a matter of seconds per year,
there is little we can do but disregard the interval, much as we arbitrarily correct the calender by
an intercalary day every four years. Thus it becomes the one passage of time of which no record
is kept other than in the changed relationship between the signs and the constellations. The
result, however, is that Sidereal Time as utilized in locating the daily noon-pint is in increasing
disagreement with Standard world-time as observed on the Earth. However, since an hour's
discrepancy as created by law during Daylight Saving Time has entailed no serious difficulties,
the failure to shift our world time zones in keeping with the precession will entail no greater
inconvenience for some 2,000 years, at which time we could relocate another observatory and
still maintain the same boundaries for our Standard Time Zones. v. Signs and Constellations

Zodiac. A circle or belt, which anciently was said to extend some 8 degrees on either side of the
ecliptic (q.v.). Modern astronomers have widened it to 9 degrees either side, because of the
extreme latitudes to which Venus and Mars attain. The position of any planet within, or of any
star within or outside of the zodiax, is measured by a perpendicular to the ecliptic. The point
where this perpendicular meets the ecliptic is the geocentric longitude of the star or planet. In a