It’s October, and the days are growing crisp and cool. The sunlight is growing shorter. Summer’s vibrant greens are melting into autumn’s brilliant hues. The gold, orange, red, yellow, and even purple leaves dance in the sunlight. We marvel at the beauty of the trees’ foliage. We rarely take time to wonder at the science and lessons behind this transformation in the trees around us.
The green color of the leaves in summer comes from chlorophyll, a substance that helps the plants absorb light energy from the sun to make food for the tree. Leaves contain other pigments, but chlorophyll’s green obscures them from our view. With autumn’s shorter hours of sunlight and cooler days, the tree prepares for winter. The tree stops making chlorophyll, and the colors of the other pigments become visible. We see yellow xanthophylls and orange carotenoids. These substances were already present within the leaf, helping the chlorophyll absorb light while protecting the leaf from damage from too much sun. Only now, as the chlorophyll breaks down, do we get to see the hidden beauty of their colors.