Which Roman god was the personification of the sky?

Caelus was the Roman god and personification of the sky. His name is related to the Latin word caelum, meaning “sky” or “heaven,” and he represented the celestial vault as a divine power.

Caelus was a primordial figure in Roman theology and was commonly treated as the Roman counterpart of the Greek Uranus. Roman writers did not always reproduce Greek mythology exactly, however. Cicero and Hyginus preserve different genealogies, including a tradition in which Caelus was the son of Aether and Dies, or “Day.”

In Roman mythological retellings, Caelus takes the role played by Uranus in the story of Saturn’s overthrow of his heavenly father. He also appeared in Roman art, including imagery associated with Augustus and later with Mithraic worship. Some representations show him as a bearded man holding a billowing cloak that forms an arch like the sky.

Uranus is the Greek equivalent, not the usual Roman answer. Jupiter was Rome’s chief sky-and-thunder god, but he was not simply the personification of the sky itself. Caelus also had no clearly established major public cult at Rome.