SALT LAKE CITY (ABC4) — Beautiful, crescent-shaped shadows can be seen during an eclipse — what are they?
As a solar eclipse draws near, you can see little crescent shadows start to appear.
According to the American Astronomical Society, as the Sun becomes a thin crescent in appearance, shadows become much sharper and more detailed. “Look at your own shadow — notice how you can see the shadows of individual hairs on your head or arms,” the organization said.
Experts say, however, anything that can cast a shadow while allowing small amounts of sunlight to peer through can create the effect of the crescent shadows. Trees are reportedly an easy way to see these shadows, due to the light passing between leaves.
It is reportedly due to a “pinhole camera effect,” which works by letting light through a tiny hole in a screen. The same phenomenon occurs when light from an eclipse passes through tree leaves. During an eclipse, not every ray of light can pass through to the ground, leaving only the rays at a certain angle to make it.
In fact, they’re tiny images of the eclipse itself.
Alternatively, and on rare occasion, “bands of shadow” can be seen across the ground during an eclipse — according to NASA, scientists still don’t know what they are exactly.
These thin, wavy lines of alternating light and dark are typically seen before and after a total solar eclipse, and they’ve reportedly been talked about throughout history.
NASA said this history dates back to the 9th century CE, described for the first time in the Völuspá, part of the old Icelandic poetic edda (collection of poems). They were reportedly also mentioned by Hermann Goldschmidt, the German astronomer and painter, back in 1820.
The history is well documented, as George B. Airy, the English astronomer, stated, “As the totality approached, a strange fluctuation of light was seen upon the walls and the ground, so striking that in some places children ran after it and tried to catch it with their hands.”
The shadows are reportedly difficult to capture, but NASA said that if you have a large piece of white paper and a proper camera setting, you might be able to catch them.
NASA explained that there have been a number of explanations for the shadows over the years. In recent history, however, experts believe that the shadows are caused by Earth’s atmosphere.
In fact, experts believe that the shadow bands seem to be related to the same phenomenon that makes stars twinkle.
“In the upper atmosphere there are turbulent cells of air that act like lenses to focus and de-focus the sharp-edged light from the solar surface just before totality. The movement of these atmospheric cells is random between each eclipse and each viewing location, so the appearance and movement of shadow bands cannot be predicted beforehand,” NASA stated.
The shadows are reportedly unpredictable from one eclipse to another, as “there does not seem to be a firm connection with the relatively fixed circumstances of an eclipse,” NASA said.
While the origins of these bands are still somewhat of a mystery, we do know that they are a phenomenon of light and motion, and that they last less than a minute before and after the slim crescent of the “solar surface” disappears.