Solar Eclipse Shadow Card

These cards are meant to show how during a solar eclipse the resolution of the edges of shadows is different in the horizontal and vertical directions as well as show multiple images of the sun through pinhole cameras of various sizes.

On a normal day the sun appears as a disk in the sky. This means that the edges of shadows appear blurry especially as the shadow gets farther away from the object casting it. This is because part of the disk of the sun can illuminate the ground leading to a partial shadow. This is called the penumbra. Penumbras are only created when the source of light is not a point source.

Near totality both before and after, only a sliver of the sun is visible. This means that in the vertical direction, the light source still appears to be the same diameter as the sun and thus horizontal shadow edges are still blurry. However, since the sun appears to be a thin sliver in the horizontal direction, the sun acts effectively as a point source in the horizontal dire