In the Spirit of Science: Casting Light on the Enchanting Will-o'-the-Wisp
Will-o’-the-Wisps, also called “ignis fatuus,” Latin for “foolish fire”, are enchanting balls of greenish-blue floating lights observed over swamps and marshes at night. At a distance, they look identical to flickering lanterns. All over the world, since ancient times, people have struggled to rationalize with the origins of these mystery lights; thus, legends and myths appear in almost every ancient culture surrounding Will-o’-the-Wisps.
Source: ancient-origins.net