Catholic view on aliens

[Walty]

It's interesting to note that if intelligent life exists, then philosophically speaking it is human - since man is defined as a 'rational animal'. This would apply equally to aliens and to us.

Theologically, it would seem difficult to say that God placed some sorts of rational animals in a different order of grace/nature (pure nature, or supernatural state and not having fallen etc). Or would it?

Though I do think the phenomenon is largely demonic though. One other possible conjecture (no evidence whatsoever for this though): ufo's are manned by our distant ancestors (probably from pre-Flood times) - that could explain why certain aliens are described as very much human looking.  

This is a pretty popular opinion these days.  I just don't know how pre-historic descendants of Cain would have lifted up off the earth and into living in space.  We're many years away from being able to do the same thing.