Ok, now I had an idea that is simple to be implemented, interesting, and that wouldn't make the UI more confusing.
Right now there are (or there will be, I don't remember) visualization tools. You can change the view to realistic, velocity, mass, etc just like in US1. Now you (dan) said that the player will be able to manually change the color of stars.
My idea is that we should add a option that shows the objects in infrared or ultraviolet light. The hotter it is, the more it will glow in infrared, until a certain point where the infrared light emitted will decrease because most of the light will be in the visible spectrum.
This can be useful to make the player understand better what is blackbody radiation and how it works. For example, when an object is very very hot, it glows blue. But if you increase the temperature even more, it will start emitting most of the light in the ultraviolet part of the spectrum, so the body would slowly seem to stop glowing (by the way, this doesn't happen in the game. But it should, because that's what happens in real life) Then you select the ultraviolet mode and you'll be able to see the super hot objects' glow.
Ok, now that's something I wanna see implemented. I'm sure of that. Also, a tutorial about blackbody radiation would be great. Well, the more educative tutorials, the better....