Top 10 optical il­lu­sions facts

Both are the same. This is the well known checker shadow illusion, first published in 1995 by Edward H. Adelson, Professor of Vision Science at MIT. The area A appears darker because of its light surrounding. At the same time, area B, surrounded with dark areas, appear lighter.

None. In this scintillating grid illusion, dark dots seem to appear and disappear randomly. Various theories have been proposed to explain it. It may be caused by the mechanism of lateral inhibition (the capacity of an excited neuron to reduce the activity of its neighbors).

Rayleigh scattering, named after the British physicist Lord Rayleigh (John William Strutt), is an elastic scattering of light or other electromagnetic radiation by particles much smaller than the wavelength of the radiation.

Small droplets or ice crystals. The effect is similar to irisation. Iridescent clouds are a diffraction phenomenon caused by small water droplets or small ice crystals individually scattering light. Larger ice crystals do not produce iridescence, but can cause halos, a different phenomenon.

Australia. This is Australia map, with north at the bottom side.

Marylin Monroe. A Hybrid Image is an optical illusion developed at MIT in which an image can be interpreted in one of two different ways depending on viewing distance. In order to see Marylin clearly, you need to move away of the screen

Africa. This map of Africa is rotated so the continent shape resembles Australia.

Red one. This is known as Poggendorff illusion, first described in 1860. Many detailed studies of the illusion point to its principal cause: acute angles in the figure are seen by viewers as expanded.

An optical phenomenon. The Fata Morgana occurs because rays of light are bent when they pass through air layers of different temperatures in a steep thermal inversion, where an atmospheric duct has formed. It significantly distorts the object on which it is based, often such that the object is completely unrecognizable. The Fata Morgana may be seen on land or at sea, in polar regions, or in deserts. It may involve almost any kind of distant objects, including boats, islands, and the coastline.

None of them. Both shapes are the same, but the bottom one is placed more to the right. This is however difficult to notice. It is known as Jastrow Illusion.