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Why is infrared astronomy best done from mountaintops, airplanes or space?

Water vapor and carbon dioxide low in the air absorb infrared.

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  1. Water vapor and carbon dioxide absorb it ✔
  2. City lights drown out infrared
  3. Infrared only travels in a vacuum

Why: Infrared is soaked up by water and carbon dioxide molecules, which are concentrated low in the atmosphere. Getting high and dry puts most of that gas below the telescope.

Huh, didn't know that: NASA flew an infrared telescope inside a Boeing 747, called SOFIA, to get above most of the water vapor.

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Infrared astronomers are always chasing new highs.
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References

Answer: Water vapor and carbon dioxide absorb it. Infrared is soaked up by water and carbon dioxide molecules, which are concentrated low in the atmosphere. Getting high and dry puts most of that gas below the telescope.

  1. OpenStax Astronomy 2e, 5.2 The Electromagnetic Spectrum openstax.org/books/astronomy-2e/pages/5-2-the-electromagnetic-spectrum
    For this reason, infrared astronomy is best done from high mountaintops, high-flying airplanes, and spacecraft.
    Checked 2026-10-10.

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