The reason I haven't been blogging lately is because I've been helping teach a retreat at IMS, which is coming to an end so I'll have time and energy to spare for a bit.
One of the things we did this time, was to chant the Dhammacakkapavattana Sutta every evening in Pali. Those familiar with this text will know that it includes near the end a list of various deva realms. This naturally got some of the retreatants curious, and some were asking questions about the various realms.
The cosmology of Buddhism is a side-alley of the Dhamma that has always fascinated me. Depending on how you count them there are five or six realms of rebirth, or thirty-three stations of existence, or three planes. The territory of the upper realms is divided between the sensual heavens, the fine-material or Brahma realms and the formless abidings.
Then there are all the fabulous beings which exist in some way on this earthly plane; yakkhas, nagas and bhumma-devas.
There isn't any one good source for a detailed road-map of the heavens; stories and anecdotes are scattered through out the canon, but especially in the Dhammapada commentary and the Jataka tales.
Various questions arise whenever this topic comes up. The first and most obvious question is also the most tedious - are they real? First of all, you tell me, what does the word "real" signify? There is a strong sense in which this mundane earthly world is a pure mental fabrication - at least the one we actually live in and experience. We get signals in the form of sense data from some hypothetical "out there" and our perception parses them and creates the world we actually inhabit.
Buddhism is essentially interested in the interior landscape, which is all we can ever really know. The world "out there" is basically a moot topic, and of little interest. Theravada has pretty much always accepted that there is an exterior world, but not all Buddhist schools have agreed. Yogacara had a mature ontology that is purely mentalist; i.e. only mind exists (hence this school is also called Citta-matra "mind only?)
Given the dubious credentials of the concept "real" to start with, it is clear that the Buddha definitely taught that the deva realms are "real." In fact, the acceptance of "spontaneously born beings" is given as one of the factors of mundane Right View. (Devas do not reproduce sexually but appear spontaneously - the lower sensual heavens do have sex, but just for fun.)
I must admit having little patience for the view that would reduce the devas and brahmas to "psychological archetypes." Assuming one has no direct knowledge of these realms, it follows that they may or may not exist. We have no objective evidence one way or the other (although to one with faith, the word of the Buddha ought to count for something.) Hence belief in these realms becomes almost an aesthetic preference. I cannot for the life of me understand why anyone would prefer to believe in a flat-land even if they can't see the third dimension. I hope this isn't too much of a spoiler, but that's essentially the point of Yann Martel's brilliant little novel, "The Life of Pi."
So let's leave that stale chesnut aside, happily assume the devas are real, and ask "where are they then?" Various possibilities present themselves; the deva realms might be present on some kind of other plane not understood by physics. Or they might simply be real three-dimensional worlds displaced from us by the fourth dimension. Or, they might actually be other planets in a different phase of evolution.
This brings up an interesting area of speculation. It is well known that ancient Indian cosmology posited a universe of multiple world-systems. To the modern mind, this correlates easily with our conception of the universe. However, I have never found an ancient text that unequivocally associates the various other worlds with the visible stars. Did they make the connection?
There is one fascinating bit of lore in the Sadhina Jataka (no. 494). In this tale, the righteous king Sadhina is fetched by Matali, the charioteer of the gods, to visit Tavatimsa Heaven. Matali takes the king on a tour of various realms on the way, which prompts Sakka, king of the gods, to declare "Doesn't Matali know that the lives of men are short?" and he sends a message to bring him along quickly. The king spends a year in heaven feasting with the gods and returns to earth, only to be arrested in the palace grounds as a trespasser. It seems that seven hundred years have passed on earth, his great-great-great etc. grandson is ruling on the throne and Sadhina is unrecognized. The really telling detail is that the time-shift seems to have occurred during the journey rather than while in heaven; hence Sakka's concern about the shortness of human life. Does any of this ring a bell?