NYX was the goddess of the night, one of the ancient Protogenoi (first-born elemental gods). In the cosmogony of Hesiod she was born of Air (Khaos), and breeding with Darkness (Erebos) produced Light (Aither) and Day (Hemera), first components of the primeval universe. Alone, she spawned a brood of dark spirits, including the three Fates, Sleep, Death, Strife and Pain.
Nyx was a primeval goddess usually represented as simply the substance of night: a veil of dark veil of mist drawn forth from the underworld which blotted out the light of Aither (shining upper atmosphere). Her opposite number was Hemera (Day), who scattered the mists of night, or Eos, the goddess of the dawn.
In ancient art Nyx was portrayed as a either a winged goddess or charioteer, sometimes crowned with an aureole of dark mist.
From http://en.wikipedia.org/wiki/Nyx_%28mythology%29 :
n Greek mythology, Nyx (Νύξ, Nox in Roman translation) was the primordial goddess of the night. A shadowy figure, Night stood at or near the beginning of creation, and was the mother of personified gods such as Sleep and Death. Her appearances in mythology are sparse, but reveal her as a figure of exceptional power.
From http://www.pantheon.org/articles/n/nyx.html :
Nyx is the goddess and embodiment of the night. According to Hesiod in his Theogony (11.116-138), "From Chaos came forth Erebus and black Night Nyx; of Night were born Aether being the bright upper atmosphere and Day Hemera, whom she conceived and bore from union with Erebus her brother". Also from the Theogony (11. 211-225); "And Night borehateful Doom Moros and black Fate and Death Thanatos, and she bore Sleep Hypnos and the tribe of Dreams. And again the goddess murky Night, though she lay with none, bare Blame and painful Woe, and the Hesperides who guard the rich golden apples and the trees bearing fruit beyond glorious Ocean. Also she bore the Destinies and ruthless avenging Fates who were regarded as old women occupied in spinning, Clotho the Spinner of the thread of life and Lachesis the Disposer of Lots, she who allots every man his destiny and Atropos She Who Cannot Be Turned, who finally cuts the thread of life who give men at their birth both evil and good to have, and they pursue the transgressions of men and of gods, and these goddesses never cease from their dread anger until they punish the sinner with a sore penalty. Also deadly Night bore Nemesis Indignation to afflict mortal men, and after her, Deceit Apate and Friendship and hateful Age and hard-hearted Strife.
From that great work we find that Nyx produced a host of offspring. Other sources give Charon who ferried the dead over the rivers of the infernal region as being the son of Erebus and Nyx, although according to the Theogony he was born from Chaos. Also according to Aristophanes, Birds 693 ff, "in the infinite bosom of Erebus, Night with black wings first produced an egg without a seed. From it, in the course of the seasons, Eros was born--the desired, whose back sparkled with golden wings, Eros like swift whirlwinds".
From http://www.timelessmyths.com/classical/primeval.html#Nyx :
Goddess of the night. Nyx was identified by the Roman as Nox, and was often just as Night. Nyx was born together with Erebus, Gaea, Tartarus, and Eros ("Love"), out of Chaos. By her brother Erebus, Nyx bore Aether ("Upper Air") and Hemera ("Day").
Nyx was also the mother of Moros ("Doom"), Thanatos ("Death"), Hypnos ("Sleep"), Charon, Nemesis ("Retribution"), and the Fates (Moerae). Nyx was possibly the mother of Eris ("Strife") and the Hesperides. Her other children were mostly abstract personification: Apate ("Deceit"), Geras ("Old Age"), the Keres ("Dooms"), Momos ("Blame"), Oizus ("Misery") and Philotes ("Tenderness"). Most of these children dwelled in the Underworld.
Nyx was sometimes seen as a winged goddess. Her wings were black or shadowy, and she was called "swift Night". She was said to dwell in the Underworld during the day, and only come out at dusk.
In the Iliad, Homer mentioned that the only goddess that Zeus only truly feared was the "all-subduing Night". Zeus would displeasure her by destroying Hypnos (Sleep), one of her many offspring.
Hmmmmm... I take some of this info with a grain of salt. As did many other goddesses, ( even more-so in Patriarchal-based cultures.) Feminine "Powers" were often misrepresented; for example Sekhmet...
Skiye, quite often Goddesses, that are associated with the Sky, are also considered Solar or Lunar deities; so perhaps you may want to expand your research to include those aspects. ; )