Geographical Longitude is measured E
Definition
Geographical longitude identifies how far a location lies east or west of the Prime Meridian at Greenwich. “Measured E” means that east longitude is counted eastward from 0° at Greenwich, generally up to 180°. A place may be written in degrees, minutes, and seconds, such as 77° 13′ E.
Astrological Meaning
Astrologers use geographical longitude, together with latitude and the exact time, to calculate a chart for a particular place. East longitude helps determine local sidereal time and therefore the positions of the Ascendant, Midheaven, house cusps, and other location-sensitive points. It does not change the planets’ zodiacal positions substantially, but it affects how those positions are oriented to the local horizon and meridian.
Why It Matters
Entering east longitude correctly is essential when erecting natal, event, electional, or horary charts. Some software uses the letter E, while other systems require east longitude as a positive or negative number; the convention should always be checked. Reversing east and west can shift the angles and houses significantly, leading to an interpretation based on the wrong local framework.
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