Do You Know?

Why you can never see the end of a rainbow?
It doesn’t have one. Theoretically, the light continues to bend into a complete circle—a circle we can’t see because it is cut off by the horizon.

Most people know the colors of the rainbow: red, orange, yellow, green, blue, indigo, violet. But few have been fortunate enough to see some of the rare manifestations of this natural phenomenon. Some rainbows are all purple, all red or even all white.
Purple rainbows are only seen before or at sunrise. They can be formed by high clouds that scatter the blue and violet light, which raindrops reflect back to the observer. At sunset, when the sun is low in the sky, a rainbow may be a dramatic red arc, because the shorter wavelengths (blue, green and yellow) have been dispersed during their relatively long trip through the atmosphere.

White rainbows can appear in daylight or moonlight, but for entirely different reasons. During the day, rays of sunlight may be reflected from very small droplets of moisture—so small that the emerging bands of color are close enough to overlap, creating white light. But a white rainbow seen by moonlight is not white at all. It only seems so because the eye cannot detect color in light as weak as what the moon is reflecting. However, a photograph of a lunar rainbow,
taken at the correct exposure, will be full in color.

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