It might seem like a simple question. But the science behind a blue sky isn't that easy. For starters, it involves something ...

Board-certified dermatologist Rebecca Marcus, MD, says research on this is still in its early stages, but it's thought that like ultraviolet (UV) light, blue light causes damage over time.

Since we can't see what an image taken in UV would truly look light, this picture is a false-color composite, with the red, green and blue shades each coming from a different ultraviolet filter.

You can use a prism to split (or disperse) white light into a spectrum of colours: red, orange, yellow, green, blue, indigo and violet. Dispersed means that the colours are separated out.