The phantom lighthouse: New research explains one of Australia's strangest illusions

There are two lighthouses on Lady Elliot Island, at the southernmost tip of Australia's Great Barrier Reef. The first was built in 1873, but was decommissioned in 1995 when the second took over the job of warning ships off the reef. Visitors to the island, however, regularly report seeing signs of a third lighthouse. At night the beams of a nonexistent phantom lighthouse are seen far off, shining on the horizon.