Age of Aquarius from astronomical perspective. First of all, we give the answer from an astronomical point of view. The International Astronomical Union (IAU) – which in the 20th century assumed the duty of officially naming and defining all things astronomical – created official constellation boundaries in 1930. From the perspective of astronomy, then, the beginning of the Age of Aquarius is based upon IAU constellation boundaries, which astrologers or New Age practitioners might or might not choose to use in their computations.
According to the Belgian astronomer and mathematical wizard Jean Meeus (bio here), who does adhere to the IAU’s definitions, the sun at the March equinox passed from being in front of the constellation Aries and to being in front of the constellation Pisces in 68 B.C. Looking ahead, again according to Jean Meeus, the March equinox will cross over into the constellation Aquarius in 2597. Once again, these are the astronomical dates, based on IAU constellation boundaries established in 1930.
Astrologers, though, might disregard the span of the constellation Pisces on the sky’s dome, and instead regard an astrological age as a precise 30o shift of the March equinox in front of the backdrop stars.
But even if you equalize the size of the signs of the Zodiac, you need to consider when the Age of Pisces started to be able to know when the Age of Aquarius begins. Apparently, there’s no firm consensus among astrologers as to when the Age of Pisces began, either. And thus there is no consensus as to when the Age of Aquarius begins. In The Book of World Horoscopes, Nicholas Campion suggests that approximated dates for entering the Age of Aquarius range from 1447 AD to 3597 AD. Campion also reviewed published material on the subject, from astrological sources. He says that most writers claim the Age of Aquarius arrived in the 20th century (29 claims). The 24th century is in second place (12 claims). Campion, by the way, is director of the Sophia Centre and Course Director of the MA in Cultural Astronomy and Astrology at the University of Wales, Lampeter. See Campion’s credentials here.
Some astrologers say the Age of Aquarius actually began in 2012. That’s because they believe the star Regulus in the constellation Leo the Lion marked the ancient border between the constellations Leo and Cancer. This star moved to within 30o of the September equinox point in 2012, meaning that Regulus left the sign Leo to enter the sign Virgo in that year. Presuming equal-sized constellations in antiquity, that places the border of the constellations Pisces and Aquarius at 150o west of Regulus, or at the March equinox point. By this reckoning, the Age of Aquarius started in 2012.
When does the Age of Aquarius begin? | Human World | EarthSky