Rainbow

A rainbow is a pretty colored arc in the sky. It happens when sunlight shines through water droplets in the air. The light bends and bounces inside each tiny water drop. This makes all the colors spread out so we can see them.

Rainbows always show up in the part of the sky across from the sun. You need the sun behind you to see a rainbow. Water droplets can come from rain, mist, or spray. Even fog can make a rainbow appear.

Sometimes a rainbow makes a full circle in the sky. But usually you only see an arc, which is part of a circle. The arc appears above the ground between you and the sun.

In a normal rainbow, red is on the outside and violet is on the inside. This happens because light bends when it goes into a water drop. Then it bounces off the back of the drop. Then it bends again when it leaves the drop.

Sometimes you see two rainbows at once. The second rainbow appears just outside the first one. In the second rainbow, the colors go in the opposite order. Red is on the bottom instead of the top.

One rainbow lasted almost nine hours long. People saw it in Taiwan in 2017. It was the longest rainbow anyone has ever seen.