geometrical horizon

geometrical horizon

[¦jē·ə¦me·trə·kəl hə′rīz·ən]
(geodesy)
The intersection of the celestial sphere and an infinite number of straight lines radiating from the eye of the observer and tangent to the earth's surface.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.