The Conventional Span and the Equinox Point

On the standard even division of the Great Year, the Age of Aries is generally placed at approximately 2000 BCE to the turn of the era, following the Age of Taurus and preceding the Age of Pisces. The constellation carries additional technical weight in Western astrology because the zero point of the tropical zodiac, the reference degree from which all twelve tropical signs are measured, is still called the First Point of Aries even though, owing to precession, it now lies within the constellation Pisces rather than Aries itself, a mismatch that is itself indirect evidence of how far precession has moved the equinox since the point was named in antiquity.

Nicholas Campion's History of Western Astrology notes that Hellenistic astrologers who developed horoscopic astrology in Ptolemaic Egypt worked within, or shortly after, the conventional Age of Aries window, and situates the astrological tradition's own origins inside the very age later writers would attach ram symbolism to, though the astrologers who systematized horoscopic technique in this period left no record of thinking of themselves as living in an "Age of Aries" in the later sense. The mismatch between the tropical zodiac's First Point of Aries and the constellation Pisces it now falls within is sometimes offered as an informal, everyday demonstration of precession's reality, independent of any position on when the associated zodiacal ages begin or end: it shows that the sky has visibly shifted against the fixed reference frame of Western astrology since the system's Hellenistic founders fixed the zero point roughly two millennia ago.