Dyḗus Pətḗr
or as I write it, Dyéus Patér. Also Dyḗus ph₂tḗr
Dyéus is the god of the Sky. The blue, bright sky of day, daylight and clouds are his natural dominion. He also fulfills the role of a Father and is the Leader of the whole pantheon (my own UPG is that he leads the déiwōs not like a king but like a father).
Dyéus is also connected to the concept of the Ártus or Hártus (with a strong h like the ch in loch). The Ártus is the universal law that underlies the cosmos, the order and beauty of it that makes life possible. Dyéus, then, upholds the Ártus and represents the concept of justice but in a cosmic and natural way (justice as in the laws of society are the dominion of another déiwos). In the trifunctional view of Proto Indo-european society, he fulfills the role of the priest-king. He's a patron of priests and the idea of doing rituals in respectful ways.
The first part of his name, Dyéus, derives from déiwos, which is the generic term for a god. So in a way he is THE god. The second part of his name, Patér, means father. Thus, seeing him as your father in the sky is totally valid (traditional even ;)!
In english his name literally means "father daylight-sky-god"
He seems to have had a connection to oaths, coming from his connection with the natural law of the Ártus.
The sun (which has its own déiwos) is sometimes referred to as "the eye of Dyéus"
Dyéus also has other names like Olyópətēr, which means All-Father, and Mitrós, which is associated with a role he had as a double deity with another god that we will see later)
Offerings
Taken from here
Feathers of either eagles or of your local highest flying birds
Depictions or imagery of clouds
Depictions or imagery of oxen
Depictions or imagery of eagles
Depictions or imagery related to fatherhood
Golden beads
Devotional acts
Mostly UPG
Cloud watching
Wearing blue
Learning about different types of clouds
Collecting feathers
Climbing a hill or mountain
Doing things related to fatherhood or leadership
Associations
Taken from here and here
Oxen
Mountain tops
The open sky
Clouds as his herd
Eagles
Feathers of high flying birds
Eye
Gold threads
Obelisk (white)
Alder
Thursday
January
Descendants in later pantheons
The deities of the Proto Indo-European (PIE) pantheon are reconstructed based on the cognates (similar names, myths and such) between later deities in different pantheons of indo-european peoples (Greek, Roman, Germanic, Nordic, Vedic, Iranian, Celtic, Slavic, Baltic, among others). As these people spread out they took their gods with them which got reshaped through generations and the evolution of language.
Dyéus is the most securely reconstructed deity of the proto indo-europeans. Here are some of his most famous descendants or versions in later pantheons:
Zeus (Greek)
Jupiter (Roman)
Tyr (Nordic)
Tiwaz (Germanic)
Diēvas (Lithuanian)
Dyaus Pitar (Vedic)
The Dagda (Celtic)
Mitra (Vedic and Iranian)
Finally, here's his wikipedia article
