Blue Sun?

I am an illustrator by trade, as some of you may know. This mostly consists of creating informative little diagrams for school science books. As a matter of professional pride I do try to get it right first time, but occasionally some slip through. It may be a spelling mistake or a part of the diagram I have had to guess about because the authors brief was sketchy, incomplete or just plain unreadable.
I received a batch of corrections today for a particularly unremarkable science title. Among these was a 'water cycle' illustration I had drawn a few weeks back. This for those of you who are unfamiliar with said 'cycle' is the process of water being evaporated from the sea, forming clouds, then raining it all back onto the land and finally dripping its way back into the ocean again.
The marked up corrections were a change of wording, and the addition of the Sun at the top above the ocean. Now the author had taken it upon themselves to give me an additional piece of information regarding putting the Sun in the sky. It was written in capital letters and had a ring around it for good measure...

It simply said 'YELLOW'

Give that person the prize for stating the BLOODY OBVIOUS!