SESKStuff Everyone Should Know
SESK: Stuff Everyone Should Know · sesk.info/astro-light-pollution-skyglow

Why does city light pollution hide faint stars?

Scattered stray light creates skyglow that lowers contrast.

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  1. It brightens the sky background ✔
  2. It moves stars farther away
  3. It cools the atmosphere

Why: Upward and sideways artificial light scatters through the atmosphere. The brighter background washes out the contrast of faint stars, nebulae, and the Milky Way.

Huh, didn't know that: The Bortle scale runs from class 1 dark skies to class 9 bright city skies.

The dad joke
City lights outshine the stars without even leaving the ground.
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References

Answer: It brightens the sky background. Upward and sideways artificial light scatters through the atmosphere. The brighter background washes out the contrast of faint stars, nebulae, and the Milky Way.

  1. Skywatching FAQ science.nasa.gov/skywatching/faq
    a glow in the night sky that makes it difficult to observe fainter stars and the Milky Way
    Checked 2026-10-10.

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