The location of the vernal point in the sidereal zodiac defines the current Astrological Age. An Astrological Age has a duration of some 2,160 years, as the vernal point (0° Aries in the Tropical Zodiac) precesses through the sidereal zodiac at a rate of something over one degree every 72 years. The two zodiacs coincided in approximately 200 AD (depending on your ayanamsa) marking the end of the Age of Aries and the beginning of the Age of Pisces. It has now precessed to around 5° Pisces, so we are gradually approaching the end of the Age of Pisces and have entered the transitional phase towards actualisation of the Age of Aquarius.