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1. one half of a sphere
a. half of the terrestrial globe, divided into northern and southern hemispheres by the equator or into eastern and western hemispheres by some meridians, usually 0° and 180°
b. a map or projection of one of the hemispheres
3. either of the two halves of the celestial sphere that lie north or south of the celestial equator
4. Anatomy short for cerebral hemisphere


(religion, spiritualism, and occult)

Hemisphere literally means a half sphere. In geography, hemisphere refers to the division of Earth into northern, southern, eastern, and western hemispheres. In astrology, hemisphere usually refers to the division of a horoscope into upper and lower halves (using the ascendant-descendant axis as the dividing line) or into left and right halves (using the midheaven-imum coeli axis as the dividing line). The upper and lower hemispheres of a chart are technically termed the diurnal (day, because it is above the horizon) arc and the nocturnal (night, because it is below the horizon) arc, respectively. The left and right hemispheres are termed the oriental (eastern) arc and the occidental (western) arc. These technical terms are rarely used by contemporary astrologers.

In the interpretation of a natal chart, the occurence of many planets above the horizon is said to indicate extroversion; many planets below the horizon indicates introversion. Also, a chart with a preponderance of planets in the left hemisphere is said to indicate an individual who shapes her or his environment, and a preponderance in the right hemisphere indicates an individual who adapts to the environment. These interpretations are tentative, “first impression” delineations and can be quickly abandoned if other factors in a birth chart give contrary indications.


Brau, Jean-Louis, Helen Weaver, and Allan Edmands. Larousse Encyclopedia of Astrology. New York: New American Library, 1980.
Gettings, Fred. Dictionary of Astrology. London: Routledge & Kegan Paul, 1985.


A half of the earth divided into north and south sections by the equator, or into an east section containing Europe, Asia, and Africa, and a west section containing the Americas.
One of the two pieces of a sphere divided by a great circle.
References in classic literature ?
And then came the great Pan-American Federation which linked the Western Hemisphere from pole to pole under a single flag, which joined the navies of the New World into the mightiest fighting force that ever sailed the seven seas--the greatest argument for peace the world had ever known.
Since that day peace had reigned from the western shores of the Azores to the western shores of the Hawaiian Islands, nor has any man of either hemisphere dared cross 30dW.
For two hundred years the Eastern Hemisphere had been wiped from the maps and histories of Pan-America.
Now, in all the Western Hemisphere dwells no man who may not find a school house within walking distance of his home, or at least within flying distance.
The direction the projectile was taking toward the moon's northern hemisphere, showed that her course had been slightly altered.
On the other hand, proceeding still further westward from the eastern islands of the tropical parts of the Pacific, we encounter no impassable barriers, and we have innumerable islands as halting-places, until after travelling over a hemisphere we come to the shores of Africa; and over this vast space we meet with no well-defined and distinct marine faunas.
Because these planets' rotation axes are tilted, their northern and southern hemispheres alternately tip toward or away from the sun.
Arrested development of the left hemisphere: The brain is divided into two hemispheres, with the left controlling language and the right responsible for visual-spatial ability, perception and expression of negative affect.
The left-brain association with tool use was strengthened by studies of two people who previously had the nerve fibers connecting their left and right hemispheres surgically severed to control severe epilepsy.
To measure neptunium-237's critical mass, the Los Alamos team cast a softball-size, 6-kg sphere of the metal that could nestle within two hemispheres of uranium.
Split-brain patients afford a unique test of possible differences in what the hemispheres do (SN: 2/24/96, p.
Morrison and his colleagues reported that, on average, there was no difference in altitude for summertime polar mesospheric clouds for the two hemispheres.