Blood and Jazz
Fürdel (lit. “fire-moon”, Elven) is the brighter and more mysterious of Ërdin‘s two major satellites. It orbits at an average distance of about 120,000 miles (193,121 km) from Ërdin’s surface.
As observed by the dark elf astronomer Enzia Kafer, Fürdel does not behave strictly in accordance with the otherwise-universal laws of orbital motion that she codified in 3499 (based on observation of Ërdel and the many systems of massive orbiting bodies periodically visible through the Veil). Instead, Fürdel’s orbit shrinks and grows every six months, moving from a large orbit about Ërdin’s equator to one of two smaller orbits at latitudes with proportionally smaller circumferences to the north and south. Kafer dubbed this unusual orbit “Kafer’s Corkscrew”, and identified it as the phenomenon responsible for the transition of Ërdin’s seasons. When Fürdel is in its northernmost position, the northern hemisphere experiences summer; when the radiant satellite is in its southernmost position, the northern hemisphere experiences winter; and when it straddles the equator, both hemispheres experience spring or autumn.
The forces responsible for Kafer’s Corkscrew are not currently well understood, though the Aexian half-elf mathematician and physicist Celuril Rafric has put forth a popular hypothesis that the unusual motion is connected to Ërdin’s complex biannual geomagnetic reversal, suggesting that Boccob might have fashioned Fürdel of a sensitive charged material that is easily nudged by planetary magnetic fields from what would otherwise be a purely gravitational orbit.