A world with a single pair of Sun and Moon was known as Mortal World because it could only birth mortals, and once a mortal broke the mortal shackle, they couldn't stay in that world any longer because the mortal world laws would start to reject them.
This process was known as ascension because those people who broke the mortal shackle would then be thrown into the worlds that could handle their power level, and the laws would be far superior to the mortal world.
These worlds would have two pairs of Sun and Moon and be known as Ascension Worlds and would be far bigger than a mortal world.
That's why when Cyrus saw the two moons but not two suns, he was a pleasant surprise because this meant this world was a Half-Ascension World and could harbor someone who had broken the Mortal Shackle!
