895

On the luminousity of the moon.

Either the moon has intrinsic luminosity or not. If it has, why does it not shine without the aid of the sun? But if it has not any light in itself it must of necessity be a spherical mirror; and if it is a mirror, is it not proved in Perspective that the image of a luminous object will never be equal to the extent of surface of the reflecting body that it illuminates? And if it be thus [Footnote 13: At A, in the diagram, Leonardo wrote “sole” (the sun), and at B “luna o noi terra” (the moon or our earth). Compare also the text of No. 876.], as is here shown at r s in the figure, whence comes so great an extent of radiance as that of the full moon as we see it, at the fifteenth day of the moon?

Taken from The Notebooks of Leonardo da Vinci edited by Jean Paul Richter, 1880.

Notebooks of Leonoardo da Vinci
XIV: Anatomy, Zoology and Physiology.
. . .
875,
876,
877,
878
The question of the true and of the apparent size of the sun.
879,
880,
881,
882,
883,
884
Of the nature of Sunlight.
885
Considerations as to the size of the sun.
886,
887,
888,
889,
890,
891
On the luminousity of the moon.
892,
893,
894,
895,
896,
897,
898,
899,
900,
901
Explanation of the lumen cinereum in the moon.
902
On the spots in the moon.
903,
904,
905,
906,
907
On the moon’s halo.
908
On instruments for observing the moon.
909,
910
On the light of the stars.
911,
912,
913
Observations on the stars.
914
On history of astronomy.
915
. . .