Question: Why do leaves change color in autumn?

Naomi Osborne answered on 26 Jun 2014:

There’s a chemical in leaves called chlorophyll that is responsible for absorbing light in photosynthesis – it’s this which makes leaves look green (because of the wavelength of light it absorbs). In autumn, there’s less light and less need for chlorophyll, so it breaks down. Usually chlorophyll masks other pigments which makes leaves look orange, yellow and red – which is why they look this lovely colour in autumn 🙂