Moon Illusion: An Observation

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Science  21 Dec 1962:
Vol. 138, Issue 3547, pp. 1340-1341
DOI: 10.1126/science.138.3547.1340


Size comparisons of the moon are made from different locations by direct viewing (as opposed to comparisons by instrumental techniques). Under the proper conditions, the illusion is seen while the moon's position remains essentially unaltered. By this means, evidence is adduced in favor of Ptolemy's apparent-distance hypothesis.