Rionus

Rionus is the planet around which Aidonia orbits. Very little is known about it and what– if anything– lies beyond its thick, hazy blue atmosphere, believed to contain a considerable amount of methane. Rionus's diameter is approximately three and a half times larger than Aidonia, and the orbital distance between the two is just shy of 300,000 miles.
Numerous attempts have been made over the years to reach the surface of Rionus via magical means, but no teleportation spells yet exist which are capable of travelling so far to a location completely foreign to the caster.
One day on Rionus lasts approximately 37.5 hours, and one year lasts approximately 215 Rionian days, or 336 Aidonian days.

Known Solar System

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This map depicts the solar system within which Aidonia exists, as astronomers currently know it. The distance between the planets and between the planets and the sun is not to scale.

Artist's Rendering of Rionus by illumiinae with Midjourney

Type

Planet