THE MOST FAMILIAR RAINBOW
The most familiar type rainbow is produced when sunlight strikes raindrops in front of a viewer at a precise angle (42 degrees). Rainbows can also be viewed around fog, sea spray, or waterfalls.
THE RAINBOW DOESN'T EXIST
A rainbow is an optical illusion—it does not actually exist in a specific spot in the sky. The appearance of a rainbow depends on where you're standing and where the sun (or other source of light) is shining.
THE COLORS OF THE RAINBOW
The colors on a primary rainbow are always in order of their wavelength, from longest to shortest: red, orange, yellow, green, blue, and violet.
RAINBOWS NEAR AND FAR
Some scientists think rainbows also exist on Titan, one of the moons of the planet Saturn. Titan has a wet surface and humid clouds. The sun is also visible from Titan, so it has all the ingredients for rainbows.