Everything you need to understand or teach Hunter's Moon by Poul Anderson.
In "Hunter's Moon," Anderson creates a background for how colonies in other solar systems might develop within the bounds of our current scientific understanding of the laws of physics. Nothing can travel faster than the speed of light; there are no "warp drives" and "hyperspace" which permit space travelers to circumvent or exceed the limits imposed by the nature of things. Messages sent by laser beams between Earth and Medea take fifty years...