Australian Aboriginal ethnoastronomical traditions were recorded from a wide variety of sources in different periods. While the corpus of mythology concerning the heavens is diverse, it is unified by beliefs of a Skyworld as land with its own topography, containing plants and animals familiar to those living below. Spirits of the dead reside alongside the Creation Ancestors as celestial bodies in the Skyworld. Aboriginal hunter-gatherers used the regular movement of constellations and planets to measure time and to indicate the season, while unexpected change in the sky was seen as an omen.