The Science of Rainbows: Understanding Spectral Phenomena

Rainbows are optical illusions caused by water droplets. Sunlight refracts within the droplets, then reflects internally and refracts again when exiting, splitting into a spectrum and forming a circular arc.

A rainbow typically displays seven colors. Red, orange, yellow, green, blue, indigo, and violet are seen due to different wavelengths of light bending at slightly different angles.

Double rainbows occur when light reflects twice inside water droplets. The secondary rainbow appears above the primary, with colors reversed and less vibrant due to the extra reflection.

Fainter, pastel bands called supernumerary rainbows can appear under a primary rainbow. They're formed by wave interference when sunlight strikes small, uniformly-sized droplets.

Red rainbows, called monochrome rainbows, happen at sunrise or sunset. The shorter blue wavelengths scatter away, leaving red hues dominating the arc.

The circular nature of rainbows often goes unnoticed because the ground obscures the lower part. From high vantage points, one can sometimes see the full circle.

Rainbows aren't exclusive to Earth. They potentially occur on any planet with sunlight and reflective moisture, but variations in atmospheric composition can alter their appearance.

Moonbows, or lunar rainbows, occur at night, created by moonlight refracting through droplets, appearing fainter and often white due to lower light intensity.