WordNet sense 1 (the apparent surface of the imaginary sphere on which celestial bodies appear to be projected):

firmament, heavens, sphere, welkin, celestial sphere, vault of heaven

WordNet sense 2 (of or relating to the sky or heavens):

empyreal

WordNet sense 3 (inspiring awe):

sublime

WordNet sense 4 (having or deserving or conferring glory):

glorious