ELI5: Why do leaves change color in fall?

Imagine Nature is a big artist, and leaves are like her canvas.

During spring and summer, Nature uses a special ingredient called chlorophyll to paint the leaves green. Think of chlorophyll as green paint. Chlorophyll is super important because it helps the leaves make food for the tree using sunlight, like giving the tree energy to grow big and strong. This process is called photosynthesis.

But as fall comes, the days get shorter, meaning less sunlight. Nature knows winter is coming, a time when it's cold and not much sunlight is available. She decides it's too hard to keep making chlorophyll, so she starts to take it back from the leaves and stores it in the tree's trunk and roots for safekeeping until next spring.

As the green chlorophyll disappears, other colors that were already in the leaves become visible! It's like the green paint fading away and showing the other colors underneath.

These colors are:

• Yellows and Oranges: Made by carotenoids, which are always there but hidden by the green.
• Reds and Purples: Made by anthocyanins, which are sometimes made in the fall when sugars get trapped in the leaves.