fast I grabbed my camera and went to port meadow to take pictures. Here are the results:
Front light:

The sun is strucking the horse. This is the picture that, for my opinion reflect the true colours of the scene.
Side light:

you can see here that the horse's body have a different colour, so as the grass which is too bright compering to my eye's sight.
Back light:

Very bad photo. As the project requested, I did try to get the sun too, but off course I would have not compose such a photo in real life.
Edge lightning:

with that horse that is what I did best as the sun and his movement didn't allow me to take a different one.
So I went to find myself a different horse which pose for me perfectly:

Here you can really see the edges glows. I love this photo.