Professional paper

The Moon Tilt Illusion

Andrea K. Myers-Beaghton ; Department of Life Sciences, Imperial College London, London, United Kingdom
Alan L. Myers ; Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania, U.S.A.

Abstract

The moon tilt illusion is the startling discrepancy between the direction of the light beam illuminating the moon and the direction of the sun. The illusion arises because the observer erroneously expects a light ray between sun and moon to appear as a line of constant slope according to the positions of the sun and the moon in the sky. This
expectation does not correspond to the reality that observation by direct vision or a camera is according to perspective projection, for which the observed slope of a straight line in three-dimensional space changes according to the direction of observation. Comparing the observed and expected directions of incoming light at the moon, we derive a quantitative expression for the magnitude of the moon tilt illusion that can be applied to all configurations of sun and moon in the sky.

Keywords

moon tilt; perspective projection; illusion

Hrčak ID:

133847

URI

https://hrcak.srce.hr/133847

Publication date:

30.1.2015.

Article data in other languages: croatian

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