The Sun's Image Across the Sphere of the Ocean
Why every point of the opposing sky sees its own image of the sun on the sea
This optical page asks why the sun's image appears to fill the whole sphere of ocean water that faces the sun. Leonardo answers that every part of the sky opposite the water sees the sun's image occupying that water, yet each point of sky sees its own separate image at a different place, so no part of the sky sees the entire reflection. Calm water illuminates the struck places equally, and the sun's image covers more of the surface the farther away the viewer stands. A diagram shows the sun, the ocean water and the reflected rays.
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Why the sun's image fills the ocean-sphere
Leonardo asks why the sun's image spreads over the whole sphere of ocean water facing the sun. All the sky opposite sees that water occupied by the sun's image, while calm water without waves illuminates equally the places its reflected rays strike.
Each point of sky sees its own image
The sun's image is single in the water-sphere yet shows itself to all the opposing sky; each point sees a separate image in a different place, so no part of the sky sees the whole, and the image covers more surface the farther the viewer stands.