According to Rig Ved Verse 1.164.33 Indra is born of Dyaus and Prithvi - the Sky Father & Earth Mother:
33 Dyaus is my Father, my begetter: kinship is here. This great earth is my kin and Mother. Between the wide-spread world-halves is the birth-place: the Father laid the Daughter's germ within it.
Again RV Verse 4.17.4 mentions:
4 Thy Father Dyaus esteemed himself a hero: most noble was the work of Indra's Maker, His who begat the strong bolt's Lord who roareth, immovable like earth from her foundation.
Verse 1.191.6 also mentions the same:
6 Heaven is your Sire, your Mother Earth, Soma your Brother, Aditi Your Sister: seeing all, unseen, keep still and dwell ye happily.
It is interesting to note that Dhara or Prithvi is also one of the Ashta Vasu so my question is - Is Dyaus Pita the same as the Dyaus mentioned as a Vasu? Additionally, is he the same person who was cursed to have been born as Bhishma?