Complex sentence: The most important ceremony of the Pawnee culture, the Spring Awakening ceremony, which was meant to awaken the earth and ready it for planting, can be tied directly to the tracking of celestial bodies.
Split into simpler sentences: The most important ceremony of the Pawnee culture, the Spring Awakening ceremony, was meant to awaken the earth and ready it for planting. It can be tied directly to the tracking of celestial bodies.