No two people ever see the exact same rainbow.

A rainbow is a personal optical illusion formed by the geometry of light. When sunlight enters a raindrop, it refracts, reflects off the back of the drop, and refracts again as it exits. This process disperses the light into its component colors at a precise angle of 42 degrees relative to the observer's line of sight.Because this angle is fixed, the 'rainbow' you see is actually a cone of light centered on your own eyes. If you move even a few centimeters, you are receiving light from a completely different collection of raindrops. This means that even your left and right eyes are technically seeing slightly different rainbows.The phenomenon was famously analyzed by René Descartes in 1637 and later by Isaac Newton, who identified the seven colors of the spectrum. Their work confirmed that the arc is not a localized object in the sky but a projection based on the observer's position. Therefore, two people standing side by side are looking at two distinct versions of the same event.This effect is further complicated by the fact that the droplets are constantly falling and being replaced by others. The rainbow you see is a continuous, dynamic event rather than a static image. Because no two people can occupy the exact same space at the same time, the light paths to their retinas will always be unique.