On cars, old, new and future; science & technology; vintage airplanes, computer flight simulation of them; Sherlockiana; our English language; travel; and other stuff
FISH DO it, bees do it. Even medieval Vikings do it: namely, use polarized light to navigate. Navigation skills in the animal kingdom have been recognized for awhile. I just learned about the medieval Viking sólarstein or sunstone in “The Crystals That May Have Helped Vikings Navigate Northern Seas,” by Steph Yin, in The New York Times, April 6, 2018.
Internet sleuthing revealed even more, including scholarly papers cited in The New York Times linking Viking sunstones with an artifact known as the Uunartoq fragment. Uunartoq? Wouldn’t you know, there’s even an online DIY piece about how to make a uunartoq. What’s more, don’t expect your homing pigeon to mimic fish, bees, or Vikings; that hypothesis has been discounted.
What follows here are tidbits on key points, split into two parts. Today, we’ll discuss the basics of polarized light and how some of the animal kingdom exploit it. Tomorrow, we’ll see how the Vikings used it to aid their navigation.
Polarized light occurs when sunlight gets filtered by particles in our atmosphere. Steph Yin’s article in The New York Times explains, “Sunlight starts out oscillating in multiple planes, but atmospheric particles create concentric rings of polarized light around the sun, even on cloudy days. Though some animals, like ants and crickets, can detect these patterns, polarization is practically indiscernible to the naked human eye.”
Natural P-ray vision is discussed at polarization.com: “Humans have some marginal sensitivity to polarized light as discovered by Haidinger in 1846, but it was not until the late 1940s that researchers realized that many animals ‘see’ and use the polarization of light.”
“In all animals, invertebrates AND vertebrates,” the article continues, “the visual pigment rhodopsin is present in the photoreceptor membrane of the visual cells.… In vertebrates, the axes of rhodopsin molecules are randomly oriented. But that is not the case in the eyes of insects.”
Other sensitive creatures. Fish, amphibians, arthropods, and octopi are sensitive to polarized light. According to polarization.com, marine creatures use it not only as a compass for navigation, but also to detect water conditions, to enhance their vision, and perhaps even to communicate.
From the late 1970s until the early 1990s, it was thought that homing pigeons also owed their navigational skills to P-rays. But a 1994 paper claimed, “The Orientation of the E-Vector of Linearly Polarized Light Does Not Affect the Behavior of the Pigeon Columbia Livia.” This appears to be the latest word on the matter.
Tomorrow, we’ll delve into research papers describing how Vikings combined polarized light with sun compasses in their navigation. Also offered is a DIY sun compass project. ds
© Dennis Simanaitis, SimanaitisSays.com, 2018