When does Uluru turn purple?

Answer 1

Uluru's colour changes depend on several factors, and the purple colour is one of those rarities that depends on certain conditions. It is most likely to happen in the late afternoon, depending on the level and degree of cloud cover at the time. The different angles of the late afternoon sun reflect off the surface of the Rock, and interact with the different soil colours surrounding the Rock, to give the deeper, dusky-red, and sometimes purple, of later afternoon. It is largely a matter of the atmospheric conditions, and how the moisture levels in the air and any clouds reflect the surrounding desert colours back onto Uluru.