The Day Out of Time marks the end of one solar cycle and the next.
The Day out of Time, which falls on July 25 each cycle, is the day before the new year.
The new year begins with July 26th and ends with July 24, only 364 days. The missing day is The Day Out of Time, giving the calendar 365 days.

This topic and others such as Day out Of Time is explained here, and perhaps you'll understand why it is celebrated.

Kin 118
White Magnetic Mirror
I Unify in order to Reflect
Attracting Order
I seal the matrix of Endlessness
With the Magnetic tone of Purpose
I am guided by my own power doubled
Castle 3: Blue Western Castle of Burning
Wavespell White Mirror

First Quarter
First Quarter