Australian Aborigines were some of the first people in the world to develop ideas with astronomy. It is possible that their interpretation of astronomy is the oldest still alive today. Studying astronomical subjects – such as the Sun, Moon, stars and planets – and the way they appeared to move was used as a way to find and explain the relationship between people, nature and the sky. The ideas that came from this contributed to their basic perception of the universe (their cosmology), and still form an important part of traditional culture and knowledge. Many legends, art forms, music and ceremonies originate from interpretations of astronomical phenomena and objects in the sky. Many Aboriginal groups give spiritual or mythological meanings to these things. Some groups used their knowledge of the movement of objects across the sky to develop practical tools like calendars.