Technically speaking, the Age of Aquarius is simply an astrological term, and not a precise one at that. Astrological (i.e. Zodiac) "Ages" refer to a period of time, approximately 2,150 years in length, and are measured by the location of the sun as it transits through one of the twelve zodiac constellations at the moment of the annual vernal equinox. The vernal equinox occurs when the sun rises above the celestial equator, which marks the start of spring in the Northern hemisphere. The sun's precessional rotation through the twelve zodiacs takes approximately 25,800 years, thus leading to the approximate 2,150-year period for each of the twelve astrological ages.
However, measuring the beginning and end point of the astrological ages is an imprecise science. This is because each of the twelve zodiac constellations varies in size and position, so astrologers do not universally agree on the delimitating point between each of the constellations, including the sun's current status between the constellations of Pisces and Aquarius.
Added to this scientific confusion is the underlying mystical meanings attributed to each of the zodiac signs and the period of time each rises in prominence. This encourages mystics and spiritualists to add their own opinions concerning the transition period between the Ages. Further, the inexact borders between the constellations have encouraged some to proclaim the transition between the Ages is not a point in time, but rather an extended period, rising slowly like a periodic tidal force. For example, Yogi Bhajan argued mystical influences of the Age of Aquarius began on 11 November 1991 and the new Age fully transitioned from the Age of Pisces on 20 November 2011.
During this period of transition, aspects and characteristics of each Age will be present, vying for dominance and slowly giving way to the characteristics of the incoming Age. Following the mystical example, the Age of Pisces could be equated with the rise of organized Western religions, Christianity and Islam, and the major impact each had on their respective and neighboring societies. Many have argued the Age of Aquarius will be defined by the rise of scientific knowledge, and with it, will transform concepts of religion to a more knowledge- and logic-based form of spirituality. Through this transformation, mankind will become more empathetic, benevolent and altruistic, and less dependent on illogical, faith-based religions or the controlling mandates of their self-appointed leaders.
Given that we are upon the period of transition between the Age of Pisces and the Age of Aquarius, the year 2012 brings with it an interesting addition to the mix. There are various eschatological beliefs concerning supposed cataclysmic events thought to be foreordained by the end-date of the 5,125-year-long cycle Mayan Long Count calendar on 21 December 2012. "Eschatology' concerns the philosophy and theology of End Times as purported by most of the world's organized religions. 21 December 2012 corresponds with the conclusion of the 13th b'ak'tun, or the end of the Mayan Long Count calendar, attributed by some theorists to have applicability to End Times' prophesies.
However, a spiritual interpretation of this confluence of events is that the period will result in a positive spiritual transformation from which 2012 will merely mark the beginning of a new, more benevolent era.
Following the principles of the Law of Attraction, one would realize humanity is in the midst of a societal tug-of-war as we approach the end of 2012. A significant portion of humanity either assumes or is worried that the end of the Mayan calendar's 13th b'ak'tun will result in cataclysmic events marking the End Times while another portion of humanity fully expects this period will result in a more spiritual-minded people on earth, though the question of "how" that transformation will occur is not addressed by this expectation. Since the Law of Attraction works more efficiently when more people share a common belief, then the potential for violent events on earth -- whether earthquakes, volcanoes, war, or the like -- increases. Since two significantly large groups of people on earth have very different expectations of the meaning of the significance of the winter solstice in December 2012, it is difficult to dismiss either camp as having no basis in probability.
However, I think it is far fetched to consider the end of humanity will occur on 21 December 2012. Even if a disaster should occur on a localized basis on the winter solstice, as occurs almost daily somewhere in the world, it is safe to assume that life will go on. Thereby, the camp of believers who expect that humanity will slowly transform and become more spiritual have the upper hand in the tug-of-war concerning the import of the end of the Mayan calendar. This is simply because the End Times believers assume an action must be initiated and completed by 21 December 2012, while the New Age believers assume the 21st of December marks a new beginning and has the next 2,150 years to reach a climax.