In Hellenistic times, especially during the 3rd century BCE, as Apollo Helios he became identified among Greeks with Helios, Titan god of the sun, and his sister Artemis similarly equated with Selene, Titan goddess of the moon. In Latin texts, on the other hand, Joseph Fontenrose declared himself unable to find any conflation of Apollo with Sol among the Augustan poets of the 1st century, not even in the conjurations of Aeneas and Latinus in Aeneid XII (161–215). Apollo and Helios/Sol remained separate beings in literary and mythological texts until the 3rd century CE.
What was the name of Apollo's sister?
Artemis