Why Do Leaves Change Color?

Here is an amazing secret: the red, orange, and yellow colors in autumn leaves were there ALL ALONG! They were just hidden behind green.

Leaves are green in summer because of a chemical called chlorophyll. Chlorophyll captures sunlight and helps the leaf make food for the tree. There is SO much chlorophyll in summer that it hides all the other colors.

But when autumn comes, days get shorter and cooler. The tree senses winter is coming and stops sending water and nutrients to its leaves. Without water, the chlorophyll breaks down and the green fades away. And suddenly — the hidden colors appear! Yellow from a chemical called xanthophyll. Orange from carotene (the same thing that makes carrots orange!). Red from anthocyanin.