“The atmosphere at times can be very unstable and very turbulent, and so we end up seeing that turbulence when we look up at the sky and the stars,” he tells Thrillist. “As those light beams go through the atmosphere, they’re kind of jiggled or move in such a manner that it would give the impression that they’re twinkling up in the sky.”
But they’re not actually twinkling, mind you. In truth, volatile pockets of air affect our perception of the stars back on the ground, giving them a shimmering, twinkling appearance when we look up at the sky.
This same phenomenon causes shadow bands to beam down to Earth from the sun, 93,000,000 miles away. As Rao explains, shadow bands are “a distortion of the final rays of sunlight, coming down through our atmosphere,” right before and after the moon completely covers the sun. During the “final moments of totality, you see these bands of light and dark, shifting, shimmering,” Rao says. So when you see a shadow band, you’re not witnessing magic, although it might appear that way. Instead, you’re seeing the edges of fleeting sunlight cutting through turbulence.