Sidereal astrology

Sidereal astrology is the system of astrology used by some Western and all Jyotish astrologers who base their interpretation around the use of the sidereal zodiac. Its primary feature is that the signs of the zodiac align to the sky constellations of the same name. The signs therefore run between dates which are different from the tropical zodiac used in the West. For example, Aries runs from March 21 to April 20 in the tropical zodiac but extends from April 14 to May 14 in the sidereal (although the precise dates may vary depending on the sidereal system used).
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