I watched the total lunar eclipse on January 20-21 in North America. Looking at it with my eyeballs it appeared red. This is due to Rayleigh Scattering. When I looked at the eclipse through binoculars and a telescope, the color was washed out, and it looked like its normal gray. Is there an obvious explanation for this?


1 Answer 1


This is strictly related to psychology, and the physiology of the eyes. Specifically, if our eyes have nothing to compare the hue of a scene too, we assume it is color balanced. Also, the retinal pigments are depleted the stronger the color energy.

  • $\begingroup$ Interesting the no comparison explanation makes sense somewhat, though I'm not exactly sure what "color balanced" means exactly. But can you explain more about depleted retinal pigments and stronger color energy? $\endgroup$
    – colorlace
    Commented Jan 28, 2019 at 14:56
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    $\begingroup$ I loosely used the term "color balanced" to mean it gets adjusted for grey scale. See photobiology.info/Crouch.html for the depletion effect (its not necessarily the original pigment, but can be a chemical intermediate in the process) $\endgroup$
    – Digiproc
    Commented Jan 28, 2019 at 16:22

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