The calendar does not rely on knowledge of the length of the tropical year or of the occurrence of leap years. It is set at the beginning of each year by observing the first full moon after the winter solstice. The first full moon also marked the date of Disting, a pagan feast and afair day, hence based by a summer and a winter side.
February 22nd. is St. Peters Day on the Runic Calender. I do not know if anybody celebrate the day St. Peter climbed the Papal Chair in Rome and became The Pope in the year 1611.
Painting of Saint Peter by Peter Paul Rubens depicting the saint as Pope (1611-1612).
The Runic Calender I have is carved on a piece of wood, I will try to keep you informed of important events from the time of the Vikings, we still have the same moon and sun, and stars to cope with, Mother Earth to take care of, and to enjoy !
It is based on Summer and Winter, not from Jan. to Dec., and from about year 1.000 to 1.800 hundred everybody had their own version to keep track of time, and we know how time can fly when you are having fun. This is a perpetual calendar, but you had to add a day once every few years, nice to take an extra day at your choice. By next full moon you could adjust.
It gives you the religious events to watch, but also the time to plant and harvest, days to celebrate, when to expect weather changes, and I assume everything they needed, until it was replaced with the Gregorian Calender, based on the Julian cycle of leap years, introduced by Pope Gregory XIII around 1500. The Catholic Church still maintain the lunar calendar to make sure Easter comes on the right day.