tell me they don’t have budget probems…go ahead 
I’m sure that fits into the general astronomical theme… 
AND…even when they put the two colors together, they’re not the same for me. I think they’re daft.
Use your hands to cover the dark squares on either side, in the explanation. The illusion persists while even partial dark squares are there. Cover them up and the illusion is gone.
Blimey. We did that in first year art. And with different colours.
Color preception is crucial for a heck of a lot of things, if ya ain’t careful it’ll come back and bite you in the…“Red Touch Yellow, Kills a Fellow. Red Touch Black, Friend of Jack” or worse “Snake of black and yellow and red, soon a stupid rhyme is said.”
What? what?
Denny,
They is crazy. And BTW, who taught them about perspective? No wonder we’re not getting back into space.
Of course, the squares have the same color density in their proof example, but their proof example is not the original drawing, where the two squares in question do not have the same shade, even when I cover up everything else on my computer screen. I have seen this and similar other examples of this phenomenon in printed form in which I did agree that actually the two squares are the same shade, even when appearing different because of the surrounding shades, but the comptuer screen presentation seems questionable to me.
yes…let’s go away with computer screens, shall we! 
Oh, alright, I give. Photoshop color pickers says they 'appear" to be the same color (RGB=120,120,120). However, this is only because they had to substitute square materials due to a warehouse shortage. Good luck always keeping that light in the same place when your wife wants to redecorate. She’s bound to notice you screwed up when you picked it up at the store.
You know, now that I know that NASA would go to all this trouble just to fake us out like this, it makes me wonder what other lies have come out of their studios…
Nevermind NASA . . . it’s the Air Force you need to be concerned about. Remember Area 52? Brrrr!
Stargate? As if Area 51 wasn’t enough trouble.
If you bring space aliens into the equation, you have a whole new ball game. By the way, I don’t see at all what any of this has to do with the health care debate in Congress. There I go being poststructural again.
Wow. I had to cut all the background out in Photoshop to believe it. Pretty cool.
Aliens ? you think we are aliens ? listen , new kid on the block ,we were here lonnnnng before you !
hah ! johny come lately !
( and Denny , that is so passé , we haven’t used those propulsion units since God was a nipper.)
sometimes they’re just embarrassing…
try this one https://forums.chiffandfipple.com/t/how-are-mchaffie-whistles/209/1
LOL! I love the smiley face, Hans 
And it is much easier to see now, thank you!
Wow, Beth, that’s awesome! 
You can really see it that way!