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Comment by globular-toast | Hacker News Reader

Something just occurred to me. Is this actually an optical illusion? My idea of an optical illusion is one where your brain perceives something that is different from reality. Indeed, when I look it up I see examples of that (e.g. https://en.wikipedia.org/wiki/Optical_illusion) But in this case your brain isn't doing anything wrong, the light reaching your eyes is what's "wrong" and your brain is correctly interpreting what your eyes see (as shown by the photograph).

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The Wikipedia article contains a helpful table [1], which classifies optical illusions. One kind are "physical" illusions, like rainbows or distortions (think stick in water). I think the hovering ship is of that kind. Other kinds include "physiological" or "cognitive", which are tricking your brain.

[1] https://en.wikipedia.org/wiki/Optical_illusion#/media/File:G...

This is a false horizon.

Your eyes are seeing the reflection of the sky on the distant water or fog, making it appear the horizon is closer than it really is.

So it is an optical illusion, as your brain is what is perceiving a horizon where it is not.

What you describe here is the usual kind of mirage, the one you see when light travels over a hot surface (desert sand, road) during summer.

This particular kind of mirage ("superior mirage", as the author of the picture calls it) works the other way around: light bends away from the cold water surface. So, of I understand it correctly, the horizon appears where it really is whereas the ship appears higher up (contrary to normal mirage where the sky appears to come from the ground).

Correction before x3n0ph3n3 has to do it again: indeed this does not appear to be either a normal nor a superior mirage.

I can only recommand to check https://m.youtube.com/watch?v=er1mh90wN-k and then https://metabunk.org/refraction/

It’s not just one person’s brain, right? Everyone who was there would see the same thing. Surely, that means our brains are pretty much wired the same. But I wonder if some people would see the “correct” thing.

What’s also mind blowing is that the camera captures the same thing your brain is interpreting!

This is proven to be a physical illusion because the light sensor (camera) is capturing the same image as the two light sensors in your head (eyes). So no person would see the "correct" thing because the light in the scene is actually rendering this image with minimal interpretive transformations from the mind (this is in contrast to cognitive illusions). Unless there is a person with some extreme sensitivity to the polarization or color of the reflected light but that is probably unlikely.

I don't have the reference handy but I recall reading years ago that certain classic optical illusions simply don't work on people who weren't raised in societies with rectangular housing.

For what it's worth, the meteorologist specifically called it a mirage, not an optical illusion. Specifically, this is a "superior" mirage, meaning that the object appears to be above its actual location.

A mirage is not an optical illusion in the way that you describe it. The BBC correspondent is the person that called it an optical illusion, not the meteorologist. :)

I think this is a very fundamental optical illusion with a focus on optical, where air temperature bends light so makes you perceive something different from what it actually is.

It's much more related to optics than direct perception. Your brain is drawing the correct image its received, the light has just been bent so that it doesn't form an accurate representation of what you're trying to see.

I think you're right, this is a mirage. The article uses both terms interchangeably.

It’s a ‘superior mirage’ technically.

It's not -- it's a false horizon.

Wikipedia uses the term optical phenomenon.

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