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Bizarre Shadows During Solar Eclipse

Oddities abound when the moon passes in front of the sun. As the sun becomes a sliver of light, the public will react to a noticeable change in lighting characteristics. It's hard to put your finger on what's different with the shadows, but something's definitely askew. If you simulate and understand the conditions beforehand you will be able to soak in the phenomenon on April 8, 2024.

For most of our lives, the sun appears as a disk and casts uniform soft shadows. You can simulate this normalcy with a circular light and a round ball that represents the moon. The shadow of the ball consists of both a dark central shadow (the umbra) and a fainter outer shadow (the penumbra).

However, for a short while during a solar eclipse the sun shrinks to a sliver of light. Importantly, that sliver is aligned along an axis. Envision it as, say, a vertical shaft of light. In our model, we can simply cover most of the circular light with a towel to reproduce this.

When we revisit the ball on a stick we can see the shadow is no longer uniform. Rather, in line with the axis of light the shadow is fuzzy, but laterally the shadow is in focus with a sharp edge.

Here are two more perspectives. Notice the shadows of the stick, too. When the stick is parallel to the axis (that is, vertical), the sides of the stick are in focus. Again, the top and bottom of the ball's shadow are soft and out of focus.

If we hold the stick perpendicular to the axis (that is, horizontally) the top and bottom of the stick shadow are out of focus, as are the upper and lower shadows of the ball.

As the size of the sun dwindles further, it gets closer to a point source of light and there is no overlapping light. When we simulate this with a fixed point of light like a Maglite in candle mode, all shadows are sharp in every direction.

So what gets all the observers so animated? While some shadows have muted edges like we experience in everyday sunshine, suddenly other shadows are exceedingly sharp and well defined. Then, as Contact 2 approaches, the light approaches a dot and everything is oddly in sharp focus. It's downright eerie.

Eclipse chaser Gordon Telepun sets up equipment to document the phenomenon of sharp and fuzzy shadows. In addition to this topic, he kindly shares a lot of his insights at the Solar Eclipse Timer YouTube channel I highly recommend his book and app ( to persons seeking to eke the most out of their Eclipse Day.

Now that you are aware of how weird shadows startle our sensibilities, please share your insight with others in the field so they too witness and understand the multiple marvels of a solar eclipse. Thanks go to Gordon Telepun for his online content and book, from which this was adapted.


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