The World of Gor

 “That is why I like to think of the planet as the Counter-Earth, not only because of its resemblance to our native world, but because, as a matter of fact, it is placed as a counterpoise to the Earth.  It has the same plane of orbit and maintains its orbit in such a way as always to keep The Central Fire between it and its planetary sister, our Earth, even though this necessitates occasional adjustments in its speed of revolution.”

Tarnsman of Gor