Changing leaves

I learned today from my teacher-wife why leaves change color. The dominant green color comes from chlorophyll. This green stuff, along with sunlight and carbon dioxide create oxygen through a process called photosynthesis. The chemicals that make other leaf colors we see in fall are always present in the leaves, they're just overpowered by the vast amounts of chlorophyll during spring and summer. (There are other factors that affect color, like the amount of sugars, but we're trying to keep it simple here.)

Once the amount of daily sunlight decreases, plants cut back on chlorophyll production, which permits those underlying colors to come out. Now you know!