Popularized by the musical Hair, "the dawning of the Age of Aquarius" is thought to usher in a collective consciousness with a resulting unity of spirit and action. There is little unity, however, on how to calculate the arrival of this next astrological age. The least complex theory holds that the present Age of Pisces began in the time of the birth of Christ, and divides the precession of the equinoxes equally among the twelve zodiac signs. By this calculation, each age is approximately 2,000 years in duration. Using a time zone where the vernal equinox--an astronomical event thought to usher in an astrological age--coincides with the rising of the sun, Calcutta, India welcomes in the Age of Acquarius in the year 2160.