Eclipse Watchers, Consider Wearing Red or Green

No, it's not Christmas in April—it's the best way to witness the 'Purkinje effect'
By Jenn Gidman,  Newser Staff
Posted Apr 5, 2024 1:59 PM CDT
Eclipse Watchers, Consider Wearing Red or Green
Stock photo.   (Getty Images/yacobchuk)

Warnings have been issued over the upcoming solar eclipse on Monday, with some areas even calling for a state of emergency. Now, a much more intriguing (and fun) phenomenon tied to the celestial event—one that involves viewers donning red and green outfits for their viewing parties to maximize the experience.

  • Purkinje effect: That's what this phenomenon is called, in which various colors appear either more muted or saturated as the amount of light changes, per CNN. Typically, vibrant reds appear darker and faded when the light is low, while greens (and blues) start to pop more.

  • Cause: It all comes down to the light receptors in our eyes. Popular Mechanics notes that our cone cells are activated during the daytime to receive light, but at night, our eyes switch over to mainly rely on rod cells. That in-between period when there's overlap is when people experience what's called "mesopic vision," leading to the color changes.
  • When it happens: It's not only during an eclipse when you can witness this for yourself—you'll see effectively the same thing, much more slowly and subtly, as late afternoon turns to dusk. The effect may appear more dramatically on Monday, due to the relative speed of the light shift during the eclipse.
  • Eclipse attire: Sporting anything red and/or green should optimize the experience. "It's April, but if people have like a Christmas shirt with red and green stripes or something, those can be really interesting to look at, having those two colors side by side and just seeing how they appear to change to our eyes," Will Snyder, manager of the James S. McDonnell Planetarium in St. Louis, tells CNN.
  • See for yourself: The Purkinje effect will be most noticeable a few minutes before totality. If you're not in the path of totality but want to experience this, computer and vision scientist Rafal Mantiuk of Cambridge University tells ScienceNews that you can take a piece of red cloth and a piece of blue cloth, look at them in the light, then dim the lights and look at the cloth pieces through sunglasses—the brightness of the squares should swap. If you do take your eclipse glasses off to see how the naked eye views this phenomenon, remember to look only at your surroundings, not the sun.
(Inmates in New York have won the right to view the eclipse.)

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