The green fireball can be seen appearing to float slowly down towards the ground before it disappears from view.
The weird phenomenon was spotted in the sky above Elford Reef, about 50km from Cairns in Queensland.
Jenny Morrison caught the baffling sight after spending a day at sea with pals.
She believes she snapped a UFO flying off Fitzroy Island, while she was sailing back to the mainland from a reef fishing trip on Saturday afternoon.