At some point in your life, you've probably played this game of logic known as the missing square puzzle, or Curry's paradox - named after its inventor Paul Curry. This optical illusion is commonly used in mathematics classes to help students reason about geometrical figures, or rather to teach them to not reason using figures, but only using the textual description thereof and the axioms of geometry. It depicts two arrangements made of similar shapes in slightly different configurations. Each apparently forms a 13×5 right-angled triangle, but one has a 1×1 hole in it.

As depicted in the animation, the illusion works because the diagonal of the two internal triangles is not a continuous slope from corner to corner. The overall connected shap [ ... ]

This type of optical illusion plays with our brain’s sense of perspective: the dragon’s face looks like it’s sticking out toward us because, after all, we know from a life time of experience that faces stick out instead of cave in.

But the exact opposite is actually the case here. Regardless of what you perceive, the entire face of this dragon is inverted making everything backwards: For example, the right eye is actually farther away from us than the left eye, and it’s this inversion that confuses our brains and makes us think the dragon is staring at us.

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This video offers up one of the strongest natural hallucinatory illusions we've ever experienced.

"We don't live in a world of reality but a world of perception." Try to read every letter on the screen...

The Schiller Effect (aventurescence) is an optical illusion that makes stones such as labradorite appear to light up internally. The layering of different minerals at a scale near the wavelength of light causes the scattering and interference effect.

This double red rainbow was photographed over a Greek sunset by Manolis Thravalos. The optical phenomena is a result of Rayleigh scattering, which is the scattering of light by tiny particles in the atmosphere. This scattering is what causes the Sun to appear yellow and the sky to appear blue, and also results in red sunsets where the atmosphere is thicker around the horizon.

Interesting!

At first glance, this photo looks like a stunning Scarlet Macaw. Look closer. This species isn’t Ara macao, it’s Homo sapiens. If you look closely, you can see her right hand as the claw, her left arm wrapped over her head to look like the head and the beak. Her left leg is outstretched to serve as the tail, while her right leg is curled up on the post. The bright green eye is painted on her forehead.

Artist Johannes Stoetter spent a month planning and executing this amazing photograph. For four hours, he painstakingly painted the model’s body with breathable paint in order to create the the beautiful details. [ ... ]