celestial sphere

Từ điển WordNet v3.1 - WordNet Dictionary

noun

the apparent surface of the imaginary sphere on which celestial bodies appear to be projected
• Syn:
sphere, empyrean, firmament, heavens, vault of heaven, welkin
• Derivationally related forms:
firmamental (for: firmament), empyreal (for: empyrean)
• Hypernyms:
surface
• Part Meronyms:
apex, solar apex, apex of the sun's way, celestial point, nadir,
zenith, zodiac