Pinhole shadows show crescent shapes in 2019 as the moon moves in front of the sun – one of many unique phenomena we can observe during a solar eclipse.
Louis Kwok /AFP via Getty Images
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Louis Kwok /AFP via Getty Images
Pinhole shadows show crescent shapes in 2019 as the moon moves in front of the sun – one of many unique phenomena we can observe during a solar eclipse.
Louis Kwok /AFP via Getty Images
If you live in the path of totality for Monday’s solar eclipse and have some Christmas or Hanukkah gear, you might want to get it out. This celestial event will bring strange phenomena to our planet, including changes in the way people perceive colors such as red, green and blue.
Here’s a look at some of the unusual visual effects a solar eclipse brings to humans on Earth:
Red and green colors will look strange
This is partly due to the change in light when the moon blocks the sun, but also to how our eyes and brain adapt and interpret this change.
Like the light darkens, our eyes shift from photopic vision, associated with cone cells in the retina that provide full colors and fine detail, to scotopic night vision that relies on rod cells to detect objects in low light conditions. In the middle is mesopic vision, the transitional phase where rods and cones are active.
As the intensity of light decreases during the eclipse, colors with longer wavelengths, such as red, will appear darker as the cones become less active. But because the rods are sensitive to shorter blue-green wavelengths, these colors will have a chance to shine.
“It’s pretty much a totality thing,” Erika Grundstrom, director of Vanderbilt University’s astronomy laboratories, told NPR, with only people in the central path of the eclipse guaranteed to be witnesses to the phenomenon.
Plus, she added, you shouldn’t rely on a single red or green T-shirt to trigger the effect.
“You have to have a lot of people (or colorful objects) around to see it,” Grundstrom said via email, adding: “The effect is the result of sudden darkness and your rods and cones trying to give a meaning to this darkness.”
This is called the Purkinje effect.
The what?
The Purkinje effect, aka the Purkinje phenomenon or shift, was documented about 200 years ago by Johannes Evangelista Purkinje, a Bohemian scientist who noticed that when light passed through a prism under dimming conditions, the brightest point shifted – s moving away from red towards blue, on the shortest point. end of the wavelength spectrum.
This effect was studied in subsequent years, including during the famous total solar eclipse of 1919, which gave scientists important observations confirming Albert Einstein’s theory of general relativity.
The penumbra should become more visible about 15 minutes before the eclipse reaches totality. For many people, light takes on a metallic or silvery quality.
Some shadows will become sharper; others will modify
On the one hand, your own shadow will be different.
“The change in lighting makes shadows sharper on the ground, so it is possible to see individual hairs on your head in your shadow,” according to the European Space Agency.
And if you see sunlight streaming through the narrow gaps in the trees, you may notice lots of little crescents. As the ESA says, “the tiny gaps in the leaves will act like multiple pinhole cameras, projecting the image of the Sun toward the ground.”
People in the path of the eclipse may also see strange reflections called shadow bands.
“A minute or two before totality, ripples of light can travel across the floor and walls as Earth’s turbulent atmosphere refracts the sun’s last rays,” as the EarthSky website reported in 2017.
Other changes to expect include a drop in temperature and the appearance of colors in the sky that will make it look like you’re seeing a sunset (or sunrise) across all 360 degrees of the horizon.
NPR News
