084 Sun setting in the Namib desert Photo by Giles Laurent

A CLOSER LOOK

Sun setting in the Namib desert, Namibia. The sun is not a perfect circle on the horizon due to atmospheric refraction, a phenomenon where Earth's atmosphere bends sunlight. As the sun appears near the horizon, its light passes through a thicker, denser layer of the atmosphere compared to when it's high in the sky. This denser air refracts, or bends, the lower edge of the sun's image more than the upper edge, causing the light from the bottom to be lifted higher than the light from the top, which squashes the sun into an oval or flattened disk. The wavy or rippled appearance of the sun's bottom edge is caused by atmospheric turbulence. While atmospheric refraction flattens the sun into an ov

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