Hemera: Greek Goddess Symbol of Light
Hemera is, in Greek Mythology, the Goddess of Light, that is, the Personification of Luminosity. She is the daughter of Nix with Erebus and in addition, this ancient goddess is also the mother of Uranus and Gaia.
Hemera in Greek Mythology:
Hemera, in Greek Myth, was the daughter of Nix (the night) with Erebo (the darkness), a primordial entity and the personification of light of the day and the morning cycle. According to the Roman poet Higino, he had a romance with his brother Ether and with him he had three children, Gaia (the Earth), Uranus (Latin: Coelus, the sky), and Tálassa (the sea). He was born with Ether and the Hespérides. Heméra's equivalent in Roman myth was Dies.
Some traditions place Ether and Heméra as parents of only Uranus and Gaia, and consequently as the "grandparents" of almost all Greek gods. According to mythology, moments before Heméra conceived Uranus and Gaia, great bangs were heard throughout the Universe, as if the sky was being influenced by the goddess (it is said that this is due to the fact that Heméra has a strong connection with Ether). After titanomaquia, Heméra started to compose the retinue of Hélio, god of the sun, next to the Hespérides. She was also the guardian of the doorways and portals between the world of light and the world of darkness.
His Children are: Gaia, Uranus and Thalassa
Who Was Thalassa:
Thalassa was, in Greek myth, one of the first pre-Olympic female personifications in the Mediterranean Sea and, by extension, the entire ocean. She was the daughter of Ether with Hêmera.
With Pontos, she was the mother of all fish and sea creatures, the nymph Hália, sometimes also the giant Egeon, the personification of the Aegean Sea and the nine Telquines.
When Uranus' semen fertilized her, she had Dione, the goddess of the nymphs. Another version places Dione as one of the oceanic and that same version places Thalassa as the mother of Aphrodite with Uranus.
Check: Meet the 9 Olympus Muses
Hemera and Nyx:
According to Hesiod, Hemera lives with his mother, Nyx, beyond the Ocean, in the far west. There, a great wall separates the gates of hell from the visible world. Behind the wall, a grand palace rises imposing where both reside, but are never seen together. When Heméra leaves, the mother waits until it is time for her daughter to return, in turn, to greet her and go out to cast the mantle of night over the world. When Nix returns to the palace, he greets his daughter and gives her permission to go out with Hélio and the Hespérides to light the land until late afternoon, and the cycle begins again. As Hesiod says, "the palace is never closed with both".
Heméra has great beauty, not as great as Aphrodite's, but enough to be considered also a goddess of persuasion and lies, who through cunning can manipulate mortals as well as other gods with some ease. It has also always been associated with the god Apollo and could even be considered as "brothers at heart", since Apollo is considered a morning solar deity.
In the book The House of Hades, from the Heroes of Olympus saga, written by Rick Riordan, Heméra is mentioned as a daughter by Nix.
Check: Nyx, the Goddess of Night