Stereoscopic Astronomy

Abstract

THE following exquisite test of the delicacy to which astronomical photography has attained may be interesting. In Admiral Mouchez's “Photographie Astronomique” (1887)—a small book, and cheap—are eight photographs of Jupiter, by the MM. Henry, taken on April 21, 1886. Several are at intervals of only three minutes in time. What with the large red spots, the irregularities of the two belts, and white spots on the upper belt, there are quite details enough to enable the eye to perceive the solidity of the planet, in a stereoscope, if the earlier picture is submitted to the right, and the later to the left eye. Reversing the order of the pictures gives a puzzling effect, which, with a little practice, is seen to be hollowness instead of solidity. But the mind resents this true result, and so gets puzzled.