OT, I know, but I couldn't find what looked like an appropriate newsgroup...

We know looking directly at the sun will damage the human eye. What
about on Mars? Jupiter? More generally, what is the threshold distance
beyond which it would be considered "safe" to look at the sun? I guess
this is a Poynting vector/physiology type question. Searching the web
just adds to the confusion. Is the distance close enough to still
resolve the sun's disk or so far away that it appears as only a point
light source?

On some afternoons, depending on clouds and atmospheric dust, the sun
looks like a giant orange ball that you can actually look at without eye
damage as it sets, but I've no idea what attenuation of its intensity
that translates into.

--
bp
Proud Member of the Human O-Ring Society Since 2003