is it correct to construct "la luno blankas," or does it work with only certain adjectives?
There's nothing wrong there that I can see. It's not the adjective, it's the verb. If the verb is a form of esti then you can strip the ending from it, throw away the radical, and glue the ending onto the correct adjective. So yes, "La luno blankas" or "La manĝaĵo bongustis" (the meal was delicious) or "Mia filino tre belos*" (My daughter will be very beautiful)
It doesn't work well with other verbs. "La luno banas la blankan pejzaĝon" for example (the moon bathes the white landscape) will in no way not accept that construction.
And a "for shame" on whoever down voted this question.
I kind of wish that Esperanto made a distinction between "the Moon" and moons in the more general sense of a natural satellite.