Ra was an ancient Egyptian sun god, chiefly associated with the noon day sun. His principle city of worship was Heliopolis.
To speak more exactly, the sun-god has two different ships: one — the Me’enzet — for the day, and the other — the Semektet — for the night; sometimes he enters the “evening ship” in the afternoon. This distinction is no more difficult to understand than the later difierentiation of the sun into three distinct personalities during the day-time, when he is called Horus (or Har-akhti, “Horus of the Horizon”) in the morning. Re’ [Ra] (his ordinary name) at noon, and Atum toward evening. The latter form, taken from the local god of Heliopolis, is depicted as human, very rarely in the oldest form of Atum as an ichneumon. The accompanying picture shows this god of the evening sun in his original animal form behind the closed western gate of heaven, built on the mountain of the west. We have already seen that the name Khepri was used for the weaker manifestations; later Re’, as the oldest name, was also employed more for the weak and aged sun; while the dying sun of evening and the dead sun of night were soon identified with Osiris, as we shall see in the chapter on the Osiris-myth.
… the most ancient and the most sacred city of Egypt, the “City of the Sun” — the Heliopolis of the Greeks — was the principal seat of the solar mythology, although the general name of the sun-god. Re’ [Ra], seems even there gradually to have replaced the old local deity, Atum, only after 2000 B.C. Heliopolis contained the earthly proxy of the tree of heaven, the holy Persea, and the sacred well which to this day is called “the Sun’s Well” (‘AIn Shams) and in which the sun was believed either to bathe himself morning and night or to have been born at the beginning of the world, when he arose from the abyss, etc. Thus the pool was not merely a type, but a real remnant of the primeval flood. Such sacred lakes were imitated in many sanctuaries, just as the sacred tree of Heliopolis had local parallels.
In all sanctuaries of the sun the god’s presence on earth was indicated by single or double reproductions of the solar ship, which sometimes were enormous constructions of stones or bricks, although generally they were made of wood and were portable, so that the priests could Imitate the daily and yearly course of the sun In solemn procession as they carried or dragged the ship around the temple or floated It on the sacred lake near by.
-Mythology of All Races, Vol 12, Egyptian