Aristotle, in Poetics, says, "the beautiful is in both the magnitude and the arrangement. Wherefore neither the very small should become a beautiful animal (for since the vision [of it] occurs in a nearly unfelt extent of time it is confused) nor should the very large (for the vision [of it] does not happen all at the same time, but the single and whole thing is gone from the vision of those who see it, if, for example, the animal should be a thousand stades long)" (1450b35ff, Thorgerson trans.).
In Plato's Timaeus, Timaeus says that the cosmos is beautiful: it is the "most beautiful of things born" (29a); the god "joined together the all so that he had fashioned a work that would be most beautiful and best in accordance with nature" (30b); and "the god wanted to make it as similar as possible to the most beautiful of things grasped by the intellect" (30d-31a).
Now I take it that the cosmos counts as a very large object. So is Aristotle disagreeing with Plato/Timaeus on this matter?
But there's more. Timaeus says that the four elements (fire, air, water, earth) are "preeminent in beauty" (53e). Naturally, these elements are very, very small (though not the smallest of things). So now Plato/Timaeus seems to also be disagreeing with Aristotle about the possibility that small things can be beautiful.
I'll look in Aristotle's De Caelo to see if he makes similar comments about the universe.
But now I wonder who's right? We might say that pace Aristotle, microorganisms are beautiful. But our saying this depends upon looking at them through a microscope, by which a larger image of the organism appears to us. So is the microorganism beautiful, or just its larger image?
Similarly for the universe. We often say that the universe is beautiful. But don't we just mean that an image (usually a picture) of some region of the universe is beautiful?
Plato's way out: Defend the position that what is most beautiful is not visible.