Your Lyin' Eyes: The Full Moon Illusion

Image froms source, Science.NASA.org

I'm a real fan of science, and also of logic. But the "full moon illusion" still eludes me. I just can't wrap my brain around it. This evening, we watched the moon rise over the Las Vegas Valley, and as it often seems when the moon is full, it looked huge. Not E.T.: The Extra Terrestrial huge, just ordinary, non-theatrical magic huge.

I've read about this optical illusion before. They tell you that the moon is always pretty much the same size, no matter where we see it in the sky. They'll tell you it's just your eyes (and your brain) playing tricks on you, and that it's just a perspective thing. You can even try a trick: extend your arm, and you can blot the moon out with your finger tip, no matter where it is in the sky. I've done the trick, and it is true.

But I've also tried to un-trick my brain, and remove the perspective issue by blotting out the landscape with my hands. And the moon still looks huge to me. When the moon is high in the sky--and looks smaller--I've tried to line it up with our roof top, or with trees or lamp posts--and it still looks smaller. I'll defer to the science, but I still don't get it. . .

[Excerpt]

Summer Moon Illusion [Editor's note: It ain't just a summer illusion!]

Sometimes you can't believe your eyes. This week is one of those times.
Step outside any evening at sunset and look around. You'll see a giant moon rising in the east. It looks like Earth's moon, round and cratered; the Man in the Moon is in his usual place. But something's wrong. This full moon is strangely inflated. It's huge!

You've just experienced the Moon Illusion.

Sky watchers have known this for thousands of years: moons hanging low in the sky look unnaturally big. Cameras don't see it, but our eyes do. It's a real illusion. . .

Read on at: Science.NASA.org