Strange Shadows ~ Images by Joanna Sulich in Rajamäki, Finland.

"I was standing in a corridor with the front door wide open in a way that rays of the setting Sun were shining through the foliage of an oak growing in front of the house and projecting shadows onto a cupboard. The shadows were moving, some were brighter some were darker, but what got my attention were the uneven edges of the shadows of my fingers."

All images ©Janna Sulich, shown with permission
Translucent chain

Rays from each hole spread because sunlight, from a 864,000 mile diameter globe, has at Earth's distance a half degree divergence.

An object like a finger inside two shafts of light casts two shadows. Where they overlap is a doubly dark zone narrower than the finger.
About - Submit Optics Picture of the Day Galleries Previous Next Today Subscribe to Features on RSS Feed
Leaves form many small holes. Ever changing.

The moving and changing shadow edges have a strange quality.   We might expect them blurred but instead they are hard edged.    There is an inner dark core, narrower than the fingers – like an x-rayed bone – surrounded by translucence.

Gaps in the shifting oak leaves are responsible.  They form an ever changing collection of holes through which penetrate shafts of sunlight.   Each shaft diverges slightly because the sun’s light comes from a disc half a degree across.    This slight spread does not matter when the holes are large.   But when they are small the individual shafts form cones or prisms depending on the hole shape.

Shadows cast by overlapping cones are peculiar.    They have a central dark area where both shadows overlap.   The dark area is narrower than the object (finger) casting the shadows.  Surrounding that are areas of only one shadow.

Add a third or fourth light shaft and the picture gets complicated indeed.

To make these patterns the leaves or other multiple hole formers must be far away compared to your fingers and screen.