If the sky is dark, it can suggest a mood of gloom; but if the sky is bright, it suggests joy. The daytime sky represents infinity and a star-studded sky is a symbol of the unconscious.
Jung saw the night sky as the most suitable place onto which people could project their unconscious desires. The symbolism of the constellations and Zodiac signs are archetypal expressions of the inner world of the unconscious. The image of a blue sky in your dreams may suggest spiritual aspirations but it is also a symbol of contentment. Most dream traditions suggest that to dream of a blue sky brings good luck, whilst cloudy skies are a harbinger of misfortune. Some claim that to dream of a red sky foretells a terrible disaster that will befall the nation.
See also SPACE AND SCIENCE.