Sol Invictus (“Unconquered Sun”) was the official sun god of the later Roman Empire and a patron of soldiers.
On 25 December 274 AD, the Roman emperor Aurelian made it an official cult alongside the traditional Roman deities. Scholars disagree about whether the new deity was a refoundation of the ancient Latin cult of Sol, a revival of the cult of Elagabalus or completely new. The god was favoured by emperors after Aurelian and appeared on their coins until the reign of Constantine I.
The identity of Aurelian’s Sol Invictus has long been a subject of scholarly debate. Based on the Augustan History, some scholars have argued that it was based on Sol Elagablus of Emesa. Others, basing their argument on Zosimus, suggest that it was based on Šams, the solar god of Palmyra on the grounds that Aurelian placed and consecrated a cult statue of the sun god looted from Palmyra in the temple of Sol Invictus. Professor Gary Forsythe discusses these arguments and adds a third more recent one based on the work of Steven Hijmans. Hijmans argues that Aurelian’s solar deity was simply the traditional Greco-Roman Sol Invictus.
Digital Maps of the Ancient World 