If you witnessed April 8's total solar eclipse, you might have noticed a mesmerizing phenomenon that occurred just before and after the celestial event.
They're called shadow bands–thin, wavy lines of alternating light and dark that move and undulate parallel on plain-colored surfaces.
According to NASA, these bands' intensity, motion, and direction seem to be related to the same spectacle that makes stars twinkle. In the upper atmosphere, turbulent cells of air act like lenses to focus and defocus the sharp-edged light from the solar surface just before totality.
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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.
Watching these shadow bands move and shimmer on the ground is fascinating. They typically appear about a minute before the total solar eclipse and last for a few seconds to a few minutes after.
The best way to view these bands is to have a plain-colored surface, such as a white sheet or a concrete pavement. The effect is most prominent in areas with good visibility and light-colored surfaces.
The phenomenon of shadow bands has puzzled scientists and eclipse watchers for centuries. Although they are not rare during a total solar eclipse, they are still not fully understood.
Some theories suggest that the shadow bands result from the interference of light waves caused by the Earth’s atmosphere. Others suggest they result from the bending of light by the Earth’s magnetic field.
So the next time you witness a total solar eclipse, which will be sometime between 2024 and 2025, keep an eye out for these elusive shadow bands and marvel at the beauty of nature's mysteries.
