Solar Eclipse Shadow Shape Explained

Valleys around the lunar limb act like pinholes projecting images of the Sun onto the surface of the Earth during the August 21, 2017 total solar eclipse. This visualization shows the projected Sun images forming a flower-like pattern with a gap in the center, where the eclipse is total.

Each edge of the umbra corresponds to a specific lunar valley on the limb. The umbra edges and their partner lunar valleys are indicated in matching colors. The ring around the Moon image on the right is an exaggerated graph of the lunar terrain on the limb.

This still image is a conceptual visualization of the geometry of a total solar eclipse. Viewed from beyond the night side of the Earth, the Moon casts its umbra and penumbra shadows onto the Earth's during the August 21, 2017 eclipse. The geometry is to scale. The position and focal length of the virtual camera were carefully chosen to capture all three solar system bodies in the frame.

This still image illustrates pinhole projection images of the Sun originating at lunar valleys along the edge of the Moon, shown conceptually as cones spreading from the Moon toward the Earth.

This still image shows the cones of pinhole projected Sun images arriving at the Earth and forming a flower-like pattern.

This still image is a closer view of the projected Sun images reaching the Earth as seen from behind the Moon. The black dot in the center of the image cones is the umbra. The outer edges of the Sun images mark the edge of the penumbra, drawn here in purple.

This still image zooms in on the umbra centered near Grand Island, Nebraska at 1 PM Central Time. The yellow arcs are the edges of Sun images projected from valleys on the edge of the Moon. They outline the umbra.

This still image illustrates the direct correspondence of each edge of the umbra shape with specific lunar valleys along the limb of the Moon.