The Moon Illusion

April 9, 2012 |

 This was the moon over Manhattan Saturday night.

It was a great example of the phenomenon known as the Moon illusion. The viewer's brain plays tricks on the eye that result in an optical illusion that the Moon is considerably larger nearer the horizon than when it's higher up in the sky. It's not larger actually, but it certainly looks like it is.
When it happens it's breathtaking to behold. One of my favorite natural phenomena.

The first time I saw it was in NYC and it was extremely low on the horizon. An absolutely gigantic sight, it was framed by the tall buildings of a crosstown street I was walking down. It looked like a huge orange beach ball sitting on the ground somewhere just across the East River.

All the pedestrian traffic stopped and everybody just stared eastward at it. In silence, mesmerized. Finally some kid asked me, "Why did the Moon land in Queens?"

I told him it was re-fueling at LaGuardia.

Judging by his nodding reaction, I think he bought it.





Speak your mind

2 Comments so far

  1. MWG on April 17, 2012 4:43 am

    Amazing picture, but this is not the “moon illusion.” You captured a shot of the moon at its monthly perigee (the point in its orbit where it is closest to earth). At 358K miles, April 7th was the 3rd closest the moon will get to earth this year and more importantly this minimum point occurred at 5pm — very near dusk. As a result, the moon actually is about 10% bigger than normal in this picture.

    Look for the moon on May 6th for another great shot although you will have to catch it around midnight (3:36am to be precise) for maximum viewing pleasure.

  2. Roger Tompkins on April 18, 2012 5:18 am

    I’ve no picture but I can tell you what happened. Riding my bicycle home from a friend’s house at sunset I was ripping along Clifton Avenue in Wichita feeling all the oats you can feel at eleven years on your new ‘English Racer’ and came to a street which required a slow down and a look to the right. So I looked. And there was the biggest, baddest orange yellow beach ball I’d ever seen parked at the end of the block of the street I wanted to cross. It covered the entire street plus at least 2-3 streets either way. It’s just that I hadn’t noticed it before, or maybe it wasn’t there before. It was the biggest thing I’d ever seen and I slammed the brakes and just looked at it as it very very slowly sank into the street. It was a mountain as round as a pie and way up in the sky. It was a soft light. My eyes were just fine, not that I cared. It was massively taller than all the houses and trees. It was bigger than anything I’d ever seen or would ever see again.

    So, you know, I kind of know what that kid meant, and what you meant, and what you saw.

    Wow — I just noticed you called your sighting a beach ball too. Yeah man, beach balls!

    It’s all good.


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