The Latin god Sol, associated with the Greek god Helios, was the deity who drove his chariot, which carried the sun, across the sky every day.
Understandably this made Sol a god of some importance to farming and crops, as well as to the taking of auspices to the ever superstitious Romans.
It is in his guise as 'Sol Invictus' that this god became a major deity in later Roman history, when he can be found on many coins. Several emperors of the later era seemed to show preference to Sol in their worship. Some might therefore see this preference for Sol Invictus as a stepping stone from a Roman pantheon littered with hundreds of gods towards Christianity with only one god.
In particular Sol's presence on the Arch of Constantine in Rome is the cause of some controversy. For if Constantine dedicated the arch to celebrate his Christian victory over the Pagan Maxentius, then why is this Pagan god depicted on the arch?