For centuries, the saying "Red sky at night, sailor’s delight ... Shorter wavelengths, like blue, scatter more easily, while longer wavelengths, like red, can penetrate through dust and moisture.

So the sky isn’t blue, at least not always. It is a glow-in-the-dark night sky too, colored a mix of green, yellow, and red. Its colors result from scattered sunlight, oxygen, and sodium from ...