Wednesday, June 18, 2008

When The Moon Hits Your Eye Like A Big Pizza Pie, That's An Illusion

There's a full moon tonight and it's going to be giant! Go see it!

The full Moon of June 18th is a "solstice moon", coming only two days before the beginning of northern summer. This is significant because the sun and full Moon are like kids on a see-saw; when one is high, the other is low. This week's high solstice sun gives us a low, horizon-hugging Moon and a strong Moon Illusion.

Sky watchers have known for thousands of years that low-hanging moons look unnaturally big. At first, astronomers thought the atmosphere must be magnifying the Moon near the horizon, but cameras showed that is not the case. Moons on film are the same size regardless of elevation. Apparently, only human beings see giant moons.

Are we crazy?

After all these years, scientists still aren't sure. When you look at the Moon, rays of moonlight converge and form an image about 0.15 mm wide on the retina in the back of your eye. High moons and low moons make the same sized spot, yet the brain insists one is bigger than the other. Go figure.

More here

Hat tip to R.

Image found here.


Willendorf Venus said...

Are we crazy?


(Well, I can't speak for anyone else.)

Aquila ka Hecate said...

I agree we're crazy - but that covers much territory!

Over here we've got the reverse conditions of course - low sun(23 and a half degrees north of 26 north of the azimuthal line makes almost 40 degrees above the horizon, believe me that's low for Sout Africa)and the moon rides high.
It was still a beautiful full moon though.
But then, they're all beautiful, just as we're all crazy.
Many solsticial blessings to you, my sisiter.
Terri in Joburg

katecontinued said...

That image is spectacular. I used it in a flyer, my blog and sent it to a friend in need.

But, when I went to the source website I was disappointed that it was actually a harvest moon, taken in mid-September. Bummer.