I am programming a solar system simulator using opengl and c++. I need some Mercator projections of the planets of our solar system.(Mercury, Venus...) I want them in .bmp format.

I know Nasa has tons of images they make available however I don't think their license would allow them to be used in another application. You might have to find a few good images of what you want then have an artist do their interpretation of the reference in photoshop if you want something that will be reused in an application.