Gene Roddenberry called over to Central Casting and asked them to send him some Aliens. But the only actors on file were a couple of earth people with pointy ears and a bevy of beauties from the planet Zeton who had the hots for Captain Kirk.
Kissing Lieutenant Uhuru, on the other hand -- is the nation ready for that?
But about sentience in our fellow travelers here on earth, I think there is a continuum. There is a kind of tiny sea worm whose brain consists of four neurons. This creature is capable of two behaviors. It goes toward light and it moves away from saltiness. I bet if it had eight neurons it could start to feel that light is beautiful and salt, not so much.
\/ (that's a hand sign)
Live Long and Prosper, fellow denizen of the Class M planet Ubertrek.

(I do have a question for you, though, given your obvious expertise on the subject of astronomy: is a "Class M" planet a real astronomical designation, or did they just make that up? :think
I do agree with you that there is a continuum for capabilities of neural response on our little blue marble. I think I referenced in an earlier post varying degrees of shared potential for emotional response (the neural and chemical phenomena that correspond to our internal sensation of "feelings") with our mammmalian brethren, the scientifically demonstrated basis for which is a certain type of development and organization of the brain that is peculiar to mammals. And that this emotional capacity is seated in the limbic system, which is our common mammalian inheritance, rather than originating in the oversized pre-frontal cortex characteristic of humans (although it is that combination, in my view, which makes "aesthetic" emotion possible).
Octopuses, which are considered to be a) mollusks and b) among the smartest (though perhaps not fully sentient) non-vertebrates on the planet, have neurological arrangements which are so different from ours that they preclude "emotions" in any way that corresponds to our own, and therefore that we ourselves can also "feel".There are good reasons why they are often (half-) jokingly referred to by biologists as "cold alien intelligences", and are possibly, and not coincidentally, the models for H.G. Wells' "War of the Worlds".
I round my way back to the essential point: if mollusks, which have been evolving on Earth every bit as long as humans/mammals, and in certain cases (e.g. octopuses) have developed capacities for intelligence that are comparable to many higher mammals (have you ever seen those vids of octopuses opening jars, "reasoning" through obstacles, "playing", "begging" for food, etc.? It's pretty amazing stuff), then the fact that they have not also developed neural capacities for emotions (which are necessarily defined as neural responses analogous to ours. If we significantly expand the concept, it becomes useless; it would be like defining an azalea bush as a car) should force us to consider the possibility (an extremely high probability, in my view) that it is in no way inevitable that sentience leads to emotion, let alone that highly specialized sub-set known as aesthetic response.
This is not to say that octopuses (and their fully sentient alien cousins) do not develop rational and understandable responses to danger, or good treatment, etc. This would be an expected outgrowth of survival imperatives and intelligence. And it's not to say that I advocate some biological bigotry; should sentient aliens ever deign to visit us, our first thought shouldn't be, I believe, to immediately blaze away with ours guns (not least because their guns might be quite a bit bigger than ours

. But sending gratuitous long-distance "Howdy, neighbor, we're here" messages via satellite is not the most brilliant idea either, in my view).
This discussion may seem OT, but OT in a localized way is not the same as irrelevant. Without recognizing that art is, on the one hand, not an activity that lacks permanent ground for making distinctions (it's not primarily "subjective", in other words), and, on the other hand, that such ground can't (or, rather, Kant) be defined by strict metaphysical criteria, but are bounded by the range of very innate human capacities and preferences (and are no less "permanent" for that), art becomes, in my view, meaningless mumbo-jumbo, and further, has no place in the competitive arena.
If the concept of PCS even survived the calamity of a universally acknowledged subjectivity, our individual griping and moaning would be as germane as saying that Patrick's Interpretation score didn't take into account the quality of his boot leather.
(Actually, I enjoy talking about stuff like this for the sheer heck of it. The last two paragraphs were added to palliate Doris' grumping

).