(1) By commemoration, we mean rituals associated with the passage of time, such as annual, monthly, or weekly events.
Some such rituals are connected with the annual passage of the sun, such as rituals on the Solar Solstice (longest day of the year) or Winter equinox (shortest day of the year).
In many societies the passage of the moon also necessitates certain rituals. The full moon is a sacred day and many places.