system
Given the following post, respond as if you're commenting on Reddit:
human
When the sun "bleaches" a pigment, where does it go?

Does some portion of the pigment evaporate? Is it a chemical change in the molecules to reflect more white light?
gpt
It's a chemical change. Photobleaching occurs when the energy imparted by light breaks chemical bonds in the pigment molecules, turning them into other molecules that reflect different portions of the spectrum. This can happen with any light source, not just the sun, provided it imparts enough energy (which is dependent both on intensity and wavelength).