During the UK's recent solar eclipse we were constantly reminded that we should never look directly at the sun because it could damage your eyesight permanently, that you should only look at the eclipse through specialist filters, with a pin-hole camera, and so on. One outlet even recommended using a kitchen colander!
But I also remember Richard Feynman writing in his book (Surely You're Joking, Mr. Feynman) that he didn't bother with the heavily darkened goggles they had given everyone who was present at the Trinity test to observe the detonation. He wrote that the only component of the blast that could physically damage your eyes was the UV emissions, and that an ordinary car windscreen was perfectly capable of blocking all the potentially harmful wavelengths.
They gave out dark glasses that you could watch it with. Dark glasses! Twenty miles away, you couldn't see a damn thing through dark glasses. So I figured the only thing that could really hurt your eyes (bright light can never hurt your eyes) is ultraviolet light. I get behind a truck windshield, because the ultraviolet can't go through glass, so it would be safe, and I could see the damn thing.
Isn't it true that it's the UV emissions of the sun that also make it dangerous to look at? Therefore, wouldn't you be safe using an ordinary sheet of glass to observe the sun? Or are there other things the sun emits that can also damage eyesight and which aren't blocked by ordinary glass?