RAINBOW

Rainbows form as sunlight shines on droplets of moisture in the Earth’s atmosphere. The droplets act like prisms, “refracting” or separating light into its component colors and sending them shooting off at a range of angles between 40 and 42 degrees from the direction opposite the sun.

Of course, rainbows are no longer scientifically mysterious. They result from the way light passes through spherical drops: it is first refracted entering each drop’s surface, reflected off the back of the drops, and again refracted as it leaves the drops, with all these rebounds giving it its final angular direction. This explanation has been known since the days of the 17th century physicist Isaac Newton. [Why Can’t We Reach the End of the Rainbow? ]

But imagine how mystical rainbows would have seemed before then! Because they are so beautiful and were so inexplicable they were featured in many early religions. In ancient Greece, for example, rainbows were thought to be the paths made by the messengers of the gods as they traveled between Earth and heaven.