There Are No Green Stars

When astrophysicists peer into the universe, they see a nearly perfect rainbow spectrum of stars, from cooler red ones on one side to hotter blue ones on the other. In the center of the spectrum, they should see green stars, but they don’t due to the nature of stars and the limitations of the human eye.

The Happy Neuron
Dec 20, 2020 · 5 min read
A picture of stars, with no green stars
A picture of stars, with no green stars
Astrophysicists can see virtually every color of star, except green.

Let There Be Light

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What the human eye can detect is only a tiny fraction of the entire electromagnetic spectrum. Radio waves have longer wavelengths and lower frequencies, which allows them to travel further. Gamma (γ) waves have much shorter wavelengths and higher frequencies, making them far more energetic and dangerous. (Creative Commons License)

The EM Spectrum and Black-body Radiation

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The color of an object is determined by the wavelengths of the majority of the light it emits in the visible spectrum. (Creative Commons License)

The Universe Staring Back at Itself

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As a star burns up its fuel, its temperature wanes, forcing it down the main sequence. Our Sun is a little over halfway through its life, putting it over halfway down. (Creative Commons License)
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The human eye detects light in a narrow band of the EM spectrum. The cones in our eyes are only sensitive to the primary colors of light: red, green, and blue. (Creative Commons License)

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