The astrological alignment happens only once every eight-hundred years, and it is said to be an event of great mystical significance, weakening the borders between the planes and allowing for great acts of magic to transpire. At the time of the Avatar's first quest against the Guardian, an impending alignment was to activate the functionality of the red titans intended gateway to Britannia - the Black Gate - which was to become operable at the exact moment the planet's aligned. 
Fortunately, the hero thwarted the Guardian's plans by using a magical transmuter to destroy the blackrock used in the gate's construction, rendering the portal useless and halting the evil entity's effort to invade Britannia at that point in time.
|“|| There was once a time when much consideration was given to the phases of the moon and the movements of the heavens. There was much concern over an event, the re-occurrence of which is eminent, called the "astronomical alignment." It was said that the astronomical alignment would create a gateway between this world and another. In recent times the astronomical alignment has been all but forgotten. With the end of the time of magic, it is doubtful that such an event will have any significance to anyone but astronomers.|
- Taking the Britannian Calendar into account, the Alignment can only happen during a double new moon, which only happens at the first of a month.