The Moon Illusion

This is maybe the biggest optical illusion everybody has seen it. The Moon is huge on the horizon and couple of hours later it shrinks to it's 'normal' size. Of many hypotheses proposed, the one defined as 'apparent distance hypothesis' is the most accurate explanation - it's simply because we humans perceive the sky as a flat or gently curved than it is in reality.

But you cannot fool the camera, cause of the simple fact that it does not have the brain and therefore if you fix  it on the tripod and take the image near the horizon and the one couple of hours later the Moon should be the same size. I always wanted to test this myself and finally my new Coolpix came with a feature of self taking images and I did it last night.

Moonrise, HDR image created by Picturenaut

So, in a nutshell, after couple of hours of shooting I took about 500 images (triggered every half a minute) and this is the result, maybe not so clear and perfect images, still this is not professional camera with good telephoto lenses, but the real size of the Moon is unchanged in all photos.

The HDR image (combined with 5 minutes difference between two images) above is created by open source application Picturenaut - since all images but first three ended in full darkness, I used first one and HDR-it with just Moons from others. The result is this combined image.


Finally here is also the video created of all images by using freeware application (ImagesToVideo) in 720p resolution. So, if you see a giant Moon rising up or giant red Sun setting down, remember it is just an illusion. Actually the reality is that both celestial bodies are actually closer when they are directly above us then next to horizon.

Refs:
Twitshot
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