The Astrology of Space - Matrix Software

The Astrology of Space
Horizon Sphere -- A heavenly sphere based on the plane
of the observer's local horizon (90° from both the zenith
and the nadir), but taken from the center of the Earth.
Zenith -- The zenith is the point directly overhead any spot
on Earth.
Nadir -- The nadir is the point directly beneath (opposite
the zenith) any spot on Earth.
Altitude -- The angular distance of any body above or
below the plane of the local horizon. Altitude is measured
from 0° to 90° from the plane of the horizon to either pole.
Azimuth -- The angle measured around the 360°
circumference of the horizon, either east or west (there are
different practices). The azimuth of an object as measured
from the meridian plane of the observer and a vertical plane
through any body.
Prime Vertical -- A great circle passing through the
zenith (north pole), nadir (south pole), and the east and
west points on the horizon.
Altitude Circles -- Parallel circles of altitude, wither
north or south of the plane of the horizon.
Almuncantar -- Parallel circles of altitude, wither north
or south of the plane of the horizon.
North Point -- A point on the horizon to the north of the
observer, where the meridian plane intersects the horizon.
South Point -- A point on the horizon to the south of the
observer, where the meridian plane intersects the horizon.
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