Telluria

Telluria is a world that exists in our universe during our current time, but is unknown to most people due to its unique position with relation to the Earth. It revolves around the sun at the same distance and speed, and in the same orbital plane as Earth, but on the opposite side of the sun. So Telluria cannot be seen from Earth, and Earth cannot be seen from Telluria.

Earth and Telluria are similar in very many ways. Telluria developed intelligent life and saw civilizations rise and fall just as Earth did. But many subtle differences between the two planets have resulted in each compiling a similar but unique history.

The same laws of physics that apply on Earth also apply on Telluria. A major difference between Earth and Telluria is Telluria's retrograde rotation, which results in the sun rising in the west and setting in the east. Another is the fact that Telluria is orbited by two mhuna instead of one moon. But the combined mass of Telluria's two mhuna is roughly equal to the mass of Earth's moon. And their orbits, combined, exert the same gravitational forces on Telluria as the moon exerts upon Earth.