Grannus is a terrestrial planet orbiting the star Caelus. The planet has a type IV atmosphere, and is unable to support life due to sulphuric rain. It's terrain is mostly comprised of volcanoes and lava rivers in no discernable pattern, with a searing hot climate. The planet is prone to regular tectonic activity, making mining resources very difficult. During the "Convergence", almost every four years Huracan and Grannus will share their atmosphere for less than three standard days. This leads to an increase in already unstable tectonics that causes jets of lava to catapult from – near, if not onto – Hurcacan.