Why do leaves change color in autumn?

A brilliant canopy of fall foliage in Bukk, Hungary. (Photo: Fesus Robert/Shutterstock)

Albert Camus once said, “Autumn is a second spring when every leaf is a flower.” It’s easy to agree with such a sentiment if you’ve ever taken a scenic autumn drive in New England or the Rockies, but what’s the science behind those breathtaking fall colors?

There are several reasons why leaves change color in the fall, but the most significant contributing factors are shorter daylight hours and longer nighttime hours, and how those factors affects the chemical process inside each leaf.

It all comes down to biological pigments (also known as “biochromes”), which are molecular substances that manifest in living things as specific colors by absorbing or reflecting wavelengths of lights…