I am currently a senior in High School. I am probably going to major in something math/physics related (engineering). I am in 3 AP classes now, AP Physics, AP Calc, and AP Computer Science.

Of the 3, I am probably the best in physics. For the comp science project however, we have to enter a programming contest. I want to make a gravity simulation, in which objects with various masses interact with one another purely gravitationally. Hopefully, I'll be able to do a runtime simulation of the solar system.

I want to make the sim in 3D. Obviously, not to scale, as doing so would probably make everything too small to see. What is the easiest free 3D API for this type of thing? I also need to learn some theory about the 3D. All I want is very basic features, load textures, move camera, move objects, very basic lighting. What would you recommend to for me to use? OpenGL? DirectX? Something else?

Any input would be appreciated.