Recently, I've been pondering what sort of consequences the existence of intelligent alien life might have for our understanding of religion here on Earth...
... religions like the various Neo-Pagan movements, Hinduism, and such focus on local manifestations of spiritual forces that theoretically could be broadened out to include other places within the universe...
... Somewhere in the middle would seem to be religions like Buddhism which, though large parts of their theology may have to be reworked in order to bring them in line with the new knowledge of intelligent life elsewhere in the universe, their general teachings would not have to change very much in order to be reconciled with this new knowledge.
The Buddha taught the existence of other world-systems with their own suns, moons, and oceans, harboring other intelligent beings. He said that our world is included in a system of 10,000 worlds, one of an infinite number of world-systems. He went on to say that Buddhas just like him sometimes appear on these worlds and teach the inhabitants the Dhamma (objective spiritual teaching and absolute Law). Sometimes they do not appear at all and the inhabitants suffer greatly for it, living through what is called a dark cosmic aeon.
Buddhist cosmology would be a helpful reference to this question.
And here I will be careful to make the distinction between the cosmology of Tibetan Buddhism and the cosmology of other countries that adopted Buddhism, and the cosmology presented by the Buddha. It's also important to note that the Buddhistic sects also honor and consider the original cosmology to be legitimate.