23 August 2017 — 1314 mdt
Flathead Memo commits eighth grade science,
measures intensity of sunlight during the eclipse
While President Trump was staring at the sun with his unprotected orbs, I was watching an image (right) of the eclipse projected through a pinhole — and using my 45-year-old Weston Master 6 light meter, which reads out in candles per square foot, to measure the intensity of the sunlight every few minutes.
My NASA designed, homebuilt, pinhole projection viewer, made from a cereal box, duct tape, and aluminum foil (Teflon coated, a slick touch), is at right. A sheet of white paper is glued to the bottom inside. A ten-cent apparatus that provided a ten-dollar view.
I measured the illumination from the sun, incident light in photographic lingo, rather than the light reflected from a gray card. The reading is the same, but measuring incident light, a standard technique in cinematography, is easier and gives more consistent results.
At the eclipse’s maximum, the sunlight was one-tenth as intense as when the sun was uncovered. That indicates the moon covered 90 percent of the sun, which was the prediction for Kalispell. I did not expect my measurements to yield such close agreement with the prediction; Lady Luck was my lab assistant.
Here are my data: