Sol in his chariot, riding across the heavens. Sol was the solar deity in Ancient Roman religion. It was long thought that Rome actually had two different, consecutive sun gods. The first, Sol Indiges, was thought to have been unimportant, disappearing altogether at an early period. Only in the late Roman Empire, scholars argued, did solar cult re-appear with the arrival in Rome of the Syrian Sol Invictus, perhaps under the influence of the Mithraic mysteries. Today, SOL is still the main word for sun in Romance languages. SOL is used in contemporary English by astronomers and many science fiction authors as the proper name of the Sun to distinguish it from other stars which may have their own planetary systems. Engraving by Jan Sadeler after Martin de Vos.