A moon cycle, or lunar cycle, is the period of time between one full moon to the next. Traditionally, lunar cycles were an important resource for the Dakota people in many ways. With guidance from the moon, the Dakota people moved seasonally, varying their work according to the time of year. Ca popapi Wi meant that it was so cold, one could hear a twig snap, or pop—hence the name, tree popping moon. The moon helped track the time for cyclical events, such as the length of seasons and peak harvest and hunting times.