There are other things in nature that are photosensitive. Cherry wood is one of them. I have to be very careful not to expose my fresh-cut wood to direct sunlight because it begins to change from a pinkish color to a reddish brown very quickly. I just finished the bed for Sasha and took the whole thing outside and exposed it to the sun so all of it would have pretty close to the same color. I even turned it around two or three times to try to even up the exposure prior to putting the tung oil finish on it.
Cherry only gets better with long exposure to light, but you can absolutely ruin a piece by, for example, leaving it out in direct sunlight with a tool sitting on a flat surface. The shadow under the tool will always be a different color from the rest unless you sand down to raw wood. And sometimes that amount of sanding will be detrimental to the flatness of say a table top.
TEd
