On this day the moon crosses the equinox from Virgo, into Libra. At that moment, Pluto and Uranus become perfectly square (90 degrees 0 minutes) to each other. It seems as if the moon is what activates the square. This will be the 4th time out of 7 exact squares between 2012-2015. Pluto being in Capricorn has to do with our government and structures, and Uranus in Aries symbolizes new beginnings. Based on this it may be apparent that this will 'not' be the end of the world, but just another step in the cycle.
5/19/2013 has had so much speculation surrounding it, I wonder if it has to do with the Pluto-Uranus square.