When we look from the bottom to the moon, we tend to believe that it is better if it is near the horizon, and less if stands high in the sky... This mysterious effect was named "moon illusion". Why does it occur, because even from ancient times people knew that the size of Earth satellite everywhere and always remain the same?

Previously, the majority of researchers have tried to explain this phenomenon by the theory of relative size. Also known as "the illusion of Ebbinghaus" - who described it in honor of the German psychologist-experimenter Herman Ebbinghaus (1850-1909).

The essence of the theory is that our brain perceives the angular size of the moon is the same as a similar size closest to the companion object. Because in the sky other comparable objects are practically absent, the Moon seems body rather small sizes. But against the background of, say, trees or mountains she looked "giantess".

Meanwhile, recently Joseph Antonides, Toshiro Kubota from Susquehanna University (USA) came to the conclusion that if you follow contrasting-dimensional theory, on the background of other objects apparent increases items should not exceed ten percent. While the horizon of the Moon "grows" twice (such effect, however, observed at rock-bottom position, and not at all latitudes). By the way, although, unlike most other optical illusion, the illusion of Ebbinghaus not lost on the photo, pictures of the Moon doesn't seem like more of its present size.

In the opinion of Antonides and Kubota, information passes through the visual centers of the brain in two different threads. The first is binocular vision. When both eyes in the brain receives the same image, the object must be far away. The higher the similarity of the images, the farther it is from us is located. In the second case the perception depends on our usual model of the world. As a rule, the celestial sphere we perceive as being from us at a remote distance, and the Sun, the moon and the stars - located in the foreground before heaven.

If binocular vision gives more or less objective view of reality (the Moon really is further from us than our nearest visible part of the sky, and the difference in distance hundreds of times), in conjunction with the second way of perceiving this is a major contradiction. To exclude, our brain tries to distort the projection of the moon, exaggerating the differences-in-picture, which arrives from one and from the other eye, and thereby distorting reliable distance options object.

The degree of distortion depends on what we think is the distance to the sky. So, if the Moon in Zenith and next to no trees and other objects, the sky seems more distant, and the satellite is small. The horizon as the distortion is minimal, allowing us to see the object on a larger scale.

To find a confirmation of his idea, the researchers plan to watch seeming changes of the moon in size in different conditions - say, in an open field, in a valley in the mountains, in the water or on the background of the urban landscape...

In addition, the researchers intend to try to figure out whether the "effect of Ebbinghaus" for people deprived of binocular vision (and it happens). Will also be checked whether the illusion disappears, if you look at the moon hanging in the sky, standing on your head (at least, that is).

I wonder why, in principle, the need to conduct such research? It would seem, what's the difference how we see so far away from us partner? The fact that Antonides and Kubota working with computer vision, and know that the characteristics of human vision is sometimes not only hinder the operator to remotely control the actions of the robot, but also hinder the adequate assessment received from the robot video observer. Thus, without taking into account these things will not be able to create any effective remote-controlled robots, nor a fully functional system that will allow you to see normally people with impaired vision. So, doing so "extravagant" problem, scientists are very practical goal.