eaves, roof, house, heaven
宇 centers on a large covering that defines a space: the eaves or roof of a house, and by extension the overarching expanse of heaven.
宇 combines 宀 (roof) with 于, which likely contributes the sound and may suggest a spreading or overarching shape. The character originally referred to the eaves of a roof and later extended to the canopy of heaven.
The roof 宀 covers the space below, and 于 looks like a hook or a spreading shape. Picture the wide eaves of a traditional house stretching out to shelter everything beneath, like the sky itself.
For ウ, imagine the eaves of a house making a long 'oo' sound as the wind blows through them: oo -> ウ, and the roof covers the space.
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universe; cosmos; space
Utsunomiya (city in Tochigi)
spaceship
bamboo stem (of a Japanese pipe)
counter for buildings, roofs, tents, etc.
microcosmos; microcosm
Utsunomiya Line
one house; one roof
god of harvests and wealth (syncretized with Saraswati, and often taking the form of a heavenly woman, a white snake or a fox)
edifice; temple; hall
Utsunomiya University
Einsteinian universe
United States Space Force
National Aeronautics and Space Administration (USA); NASA
inflationary universe
James Webb Space Telescope
Hubble Space Telescope
big bang theory (cosmology)
Fermi Gamma-ray Space Telescope
primary cosmic rays