Career
He competed for the Soviet Union in the decathlon at the 1964 and 1968 Olympics, winning a silver medal in 1964. Their father died when Aun was just 13. He attended a sports school, where he trained in long-distance running before changing to decathlon.
Domestically, he held the Soviet decathlon titles in 1967-1968 and finished second in 1964.
In retirement he coached athletics and served as the secretary-general of the Estonian Athletics Association.