Remember on Venus how there's those neat blue lava flows and big blue volcano in the distance? Probably thought, "Gee, what neat sci-fi nonsense. (Like these enormous super bats!)". As it turns out though, it's not actually as much nonsense and you would think. Venus has a lot of sulfur. As it turns out when sulfur burns it burns blue. Lots of hot lava combined with sulfuric gases makes what appears to be blue lava. Conditions for this to happen actually occur right here on Earth, most notably at the volcanic crater Kawah Ijen. This blue lava is only visible at night however due to that the bright white light from the Sun simply overpowers the blue light emitted from the burning sulfur. Venus' extremely thick atmosphere however blocks most visible light from getting through so the Sun's impact could be reduced to the point that the burning sulfur appears blue all the time. Neat to think they did that level of research before designing the map. Now about that Sun on Mercury though...