Those circles betray their source. Beneath a Japanese maple, some bright patches reproduce the Sun's round face rather than the pointed leaves overhead, because small openings between leaves act as pinhole projectors. The leaves supply the apparatus. What reaches the ground is not simply a stencil of their edges, but an image formed by sunlight passing through a restricted aperture.
Distance does the editing. Each point on the Sun sends light through a gap at a slightly different angle, so the resulting patches overlap into a small image of the solar disk. No lens is needed. This process, called pinhole projection, works best when the opening is small compared with its distance from the receiving surface, allowing the Sun's angular diameter to dominate the patch's outline. Size sets the limit. The Sun spans about half a degree in the sky, producing an image roughly nine millimeters across for every meter of projection distance.
Not every patch qualifies. Close beneath an opening, or beneath a large gap, the bright area more closely resembles the opening itself; farther away, the solar image becomes easier to distinguish, though its edges remain blurred. Smaller is not unlimited. An extremely tiny aperture introduces diffraction, which spreads light and softens the image rather than sharpening it indefinitely, while a tilted receiving surface can stretch a circle into an ellipse. The sharp leaves recede. Beneath their serrated canopy, the ground holds a quieter portrait of the star that makes the whole scene visible.
