Cleomedes(1st Cen. B.C.) on the Lunar Eclipse With Both the Sun and Moon Above the Horizon

“The history of Greek astronomy furnishes a good example of this, as well as of the fact that no visible phenomenon escaped their observation. We read in Cleomedes [Cleomedes, De motii circulari, ii. 6, pp. 218 sq. – On the Circular Motions of the Celestial Bodies] that there were stories of extraordinary lunar eclipses having been observed which ‘ the more ancient of the mathematicians ‘ had vainly tried to explain ; the supposed ‘ paradoxical ‘ case was that in which, while the sun appears to be still above the western horizon, the eclipsed moon is seen to rise in the east. The phenomenon was seemingly inconsistent with the recognized explanation of lunar eclipses as caused by the entrance of the moon into the earth’s shadow ; how could this be if both bodies were above the horizon at the same time ? The ‘ more ancient ‘ mathematicians tried to argue that it was possible that a spectator standing on an eminence of the spherical earth might see along the generators of a cone, i.e. a little downwards on all sides instead of merely in the plane of the horizon, and so might see both the sun and the moon although the latter was in the earth’s shadow. Cleomedes denies this, and prefers to regard the whole story of such cases as a fiction designed merely for the purpose of plaguing astronomers and philosophers ; but it is evident that the cases had actually been observed, and that astronomers did not cease to work at the  problem until they had found the real explanation, namely that the phenomenon is due to atmospheric refraction, which makes the sun visible to us though it is actually beneath the horizon. Cleomedes himself gives this explanation, observing that such cases of atmospheric refraction were especially noticeable in the neighbourhood of the Black Sea, and comparing the well-known experiment of the ring at the bottom of a jug, where the ring, just out of sight when the jug is empty, is brought into view when water is poured in.”

A History of Greek Mathematics by Sir Thomas Heath, pgs. 6-7


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