Art. LI.—On a Stereoscopic Aspect of the Moon.
[Read before the Hawke's Bay Philosophical Institute, 15th August, 1887.]
The full moon presents the appearance of a disc, not of a sphere, to most if not all people, and I have never met with any other description of her appearance. But, by a little ingenuity, a truly stereoscopic view of our satellite may be had. If, when the full moon is on or near the meridian the light is conceived to fall upon her from above, and to the left, the darker portions on the opposite side fall into the positions of shadings natural to a sphere so illuminated under ordinary circumstances, and the visible surface stands out boldly as a hemisphere. The photograph of the full moon in Proctor's “Moon” will give this effect, but less distinctly than the orb itself, the dark portions being too dark, perhaps. Having once seen this solid aspect of the full moon, it always presents itself, at least to me. If this is a new and not a re-discovery, and wonder is felt that it was not observed before, the obvious explanation is that the moon is upside down, so to speak, to the inhabitants of the Northern Hemisphere, where observers, till of late years, have lived; and they must lie down, or stand on their heads, to get the view of it that we have, or suppose the unusual condition of the sphere being illuminated from below.