Mondas

Mondas was the twin planet of Earth and original homeworld of the Cybermen. In ancient times, it was dislodged from its old position out into space when the Moon was formed. The Cybermen eventually learned to pilot their planet and took Mondas back to Earth, where it was destroyed.
== Geography ==
Mondas was identical to Earth, even down to the size and shapes of its continents. The one major way that it differed to Earth was that its continents were upside down in relation to Earth. However, it had no visible clouds in its atmosphere at that time. (TV: The Tenth Planet)
== History ==
=== Creation ===
Originally, Earth and Mondas occupied the same orbit in the solar system. It was stated that "Mondas" was another name for Earth in one of the ancient languages. (TV: The Tenth Planet)