Many animals, including bees, birds and even mammals like reindeer and mice can perceive ultraviolet light. Indeed, the lack of UV-sensitivity in humans is more of an exception than the rule. At the other end of the visible light spectrum, human eyes have receptors that are sensitive to red while many animals—including bees, mice and dogs—are just as blind to red as we are to ultraviolet light.

Even when it comes to blues and greens, colors perceived across the animal kingdom, the precise wavelength of the light an animal would experience as "pure blue" or "pure green" is specific to the species. As a result, no two species see the world in the same colors.

We invite you to stare at the sky and appreciate that its blueness is the joint product of the sunlight being scattered in the atmosphere and your own sensory system. The color you see is specific to you—in fact, for many animals, the sky is ultraviolet-colored.