I was looking at this the other night, when earth-moon-mars was in a straight line, and was able to mentally mirror the shape of the illuminated portion of the gibbous moon onto mars as well, was pretty cool. Now that I think about it though, that was incorrect, mars would have been closer to a circle from my pov because it's 15 degrees or whatever further around the sun right now. If the light source was much further away, it would have been right.
