Beauty is in the eye of the beholder. And in case of a whole alien species, by pure probability, they would likely be used to a red sky and black plants (red dwarfs (more infrared) being the most numerous among the stable stars). Or even find a free sky horrendous and feel similar about rolling green hills like we feel about Nausicaa’s fungal forests.

But Avatar (the Pandora one) did a good job at imagining a different but similiar kind of nature.