He soon realized that the Nazca Lines were too shallow to have acted as part of the irrigation system. On a flight over them, Kosok realized that one pattern represented a bird. He also noticed that some of the lines converged on that date of the winter solstice in the Southern Hemisphere. This inspired his study of the lines to assess if they were related to astronomy, as he knew that solar events were closely followed by ancient agricultural societies for their planting cycles.