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SESK: Stuff Everyone Should Know · sesk.info/astro-fraunhofer-lines

In 1815, Joseph Fraunhofer counted about how many dark lines in the Sun's spectrum?

About 600.

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  1. About 6
  2. About 600 ✔
  3. About 60,000

Why: The dark lines are colors missing from sunlight, absorbed by atoms in the Sun's cooler outer gas. Each element leaves its own pattern, which later let astronomers read what stars are made of.

Huh, didn't know that: William Wollaston saw a few of these lines first but thought they were just boundaries between colors.

The dad joke
Fraunhofer kept drawing lines in the Sun's spectrum. He had no boundaries.
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References

Answer: About 600. The dark lines are colors missing from sunlight, absorbed by atoms in the Sun's cooler outer gas. Each element leaves its own pattern, which later let astronomers read what stars are made of.

  1. OpenStax Astronomy 2e, 5.3 Spectroscopy in Astronomy openstax.org/books/astronomy-2e/pages/5-3-spectroscopy-in-astronomy
    German physicist Joseph Fraunhofer , upon a more careful examination of the solar spectrum, found about 600 such dark lines
    Checked 2026-10-10.

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