St. Elmo's Fire is an electrical phenomenon in which plasma (ionized gas) is created from an object in an atmospherical electrical field such as a thunderstorm. Named after St. Erasmus of Formiae, the patron saint of fire, St. Elmo's Fire often occurred on the masts of sailing vessels following a terrifying storm. During Magellan's circumnavigation of the world, the sailors believe that the presence of St. Elmo's Fire was a divine sign leading them to continue on their journey.