The newest headcanon that I made just this morning with absolutely zero proof is that the moons are linked together across all shards. Which is why when we see the ascians bring Cyella, Unukalhai, and Ardbert across the rift to influence another shard it's always on the surface of the moon. That the teleporter isn't just for travel to and from the surface. And, why in one of the more recent lore Q&A's SE was cagey about talking further about the celestial bodies.