A rainbow is an arc of colour in the sky that can be seen when the sun shines through falling rain. The pattern of colours, called a spectrum, starts with red on the outside and changes through orange, yellow, green, blue, indigo, and violet on the inside. Sometimes a second, larger, dimmer rainbow is seen.
A rainbow is created when white light is bent (refracted) while entering a droplet of water, split into separate colours, and reflected back. A rainbow is actually round like a circle. On the ground, the bottom part is hidden, but in the sky, like from a flying airplane, it can be seen as a circle around the point opposite the Sun.
Rainbows often appear after storms, and are popular symbols for peace in many cultures.